DESC:
Field of the invention
The present invention relates to a process for preparation of Janus kinase inhibitors. More particularly the present invention relates to the process for preparation of Ruxolitinib and salts thereof.

Background of the invention
Ruxolitinib of formula (I), is chemically known as (3R)-3-Cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propanenitrile. It is a potent and selective inhibitor of Janus associated Kinases (JAKS) JAK1 and JAK2.

It is approved by the FDA for the treatment of intermediate or high-risk myelofibrosis including primary myelofibrosis (PMF) and post-polycythemia vera-myelofibrosis (PPV-MF) and post essential thrombocythemisa.

Ruxolitinib and its pharmaceutically acceptable salts and the process for its preparation is first disclosed in US pat. No. 7,598,257. The patent discloses process as shown in scheme below for the preparation of Ruxolitinib of formula-I.

However, the process involves the separation of racemic compounds using preparative HPLC. Further, the obtained compounds as well as the (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propanenitrile of formula-I were purified by column chromatography. Use of preparative HPLC and column chromatography for industrial production is time consuming, troublesome and economically not feasible.

(3R)-3-Cyclopentyl-3-[4-(7H-pyrrolo[2,3-d] pyrimidin-4-yl) pyrazol-1-yl] propanenitrile phosphoric acid salt is specifically first disclosed in US pat. No. 8,722,693. The process involves reacting (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propanenitrile with phosphoric acid followed by isopropyl alcohol. The resulting mixture was heated to clear, cooled to room temperature, and then stirred for another 2 hours. The precipitate was collected by filtration and the cake was washed with cold isopropyl alcohol. The cake was dried under vacuum to constant weight to provide the (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propanenitrile phosphoric acid salt. The process does not report preparation of (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl] propanenitrile.

Prior art procedures of resolving R-Ruxolitinib or it’s N-protected analogue, use resolving agents like (2S,3S)-2,3-bis(benzoyloxy)butanedioic acid i.e. (+)-dibenzoyl-D-tartaric acid (CAS# 17026-42-5), (2S,3S)-di-4-toluoyltartaric acid i.e. (+)-di-p-toluoyl-D-tartaric acid (CAS# 32634-68-7) both of which are prepared from D-tartaric acid.

PCT application WO2016035014 discloses resolution of 3-(4-(7H-Pyrrolo[2,3-d]pyrimidin-4-yl)-lH-pyrazol-l-yl)-3-cyclopentylpropanenitrile with (+)-2,3-Dibenzoyl-D-tartaric acid. The number of purification steps required in the process involves 6 steps and provides very low yield which is about 6.97%.
Another PCT application WO2016026975A1 discloses preparing 3 ((R)-3-Cyclopentyl-3-{4-[7-(2-trimethylsilanyl-ethoxymethyl)-7H- pyrrolo[2,3-d]pyrimidin-4-yl]-pyrazol-l-yl}-propionitrile) by reacting (rac-3-Cyclopentyl-3-{4-[7-(2-trimethylsilanyl-ethoxymethyl)-7H- pyrrolo[2,3-d]pyrimidin-4-yl]-pyrazol-l-yl}-propionitrile) with (+)-2,3-Dibenzoyl-D-tartaric acid. Both of process in the prior art have used D-isomer with multiple steps for purification. The number of purification steps required in said process involves 4 steps and provides only 18.54% yield.

Both the patent application disclosed at least 5 purification steps to achieve chiral purity. These extra purification steps are necessary for obtaining a pure yield of the product. However, repeated purification steps also result in yield loss which ultimately contributes to the cost of production of the final compound Ruxolitinib.

Thus, there is a need to overcome the problem of prior art by providing an economical process for preparation Ruxolitinib and salts thereof having high chiral purity.

Summary of the invention
The present invention discloses a process for preparing Ruxolitinib i.e. R and S forms of Formula (I) by treating Formula (II) with a resolving agent, di-anisoyl tartaric acid of formula (RA). (R)-Ruxolitinib is (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile and (S)-Ruxolitinib is (3S)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile.
.
Accordingly, in general aspect, the present invention provides a process for preparation of Ruxolitinib (I) comprising reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with a resolving agent, di-anisoyl tartaric acid (DATA) of formula (RA),
, ,
wherein P1 is selected from H and suitable protecting group,
, .
In one aspect, the present invention relates to a process for preparing Ruxolitinib of formula (I), said process comprises reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with a resolving agent, di-anisoyl tartaric acid (DATA) of formula (RA), wherein the di-anisoyl tartaric acid (DATA) of formula (RA) is L-di-anisoyl tartaric acid of formula L (RA) for preparing R-Ruxolitinib or D-di-anisoyl tartaric acid of formula D (RA) for preparing S-Ruxolitinib,
, .
The ratio of the resolving agent with respect to racemic compound of formula (II) is 0.4 to 1.8 preferably 0.4 to 0.8.

In one aspect, (R)-Ruxolitinib can be obtained by treating compound of formula (II) with a resolving agent L-di-anisoyl tartaric acid of formula L (RA).
In another aspect, (S)-Ruxolitinib can be obtained by treating compound of formula II with a resolving agent D-di-anisoyl tartaric acid of formula D (RA).

In one aspect, present invention provides a process for preparing (R)-Ruxolitinib,

comprising the steps of:
a) reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with L-di-anisoyl tartaric acid of formula L(RA), in presence of a solvent at a temperature in a range from 20-85°C, and forming a mixture of a compound of formula (IIIS) and L-di-anisoyl tartarate salt of formula (IIR) in a ratio of 0.6:0.4 to 0.5:0.5,
+ ;
b) separating L-di-anisoyl tartarate salt (IIR) from compound (IIIS) by filtration and obtaining the L-di-anisoyl tartarate salt (IIR) in precipitate and compound (IIIS) in filtrate;
c) reacting the L-di-anisoyl tartarate salt (IIR) obtained in the precipitate with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C and isolating compound of formula (IIIR)
’
wherein P1 is selected from H or a protecting group,
and
d) purifying compound (IIIR) in a solvent at a temperature in a range from 50 to 80°C to obtain (R)-Ruxolitinib.
The protecting group is selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
The solvent for purifying compound (IIIR) is selected from the group comprising aprotic solvent, alcoholic solvent, ketonic solvent, ester solvent, etheral solvents, chlorinated solvents, hydrocarbon, and the mixtures thereof. The aprotic solvent is selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent is selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent is selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent is selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon is selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent is selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile alone or in combination thereof.
The ratio of the L-di-anisoyl tartaric acid of formula L(RA) with respect to racemic compound of formula (II) is 0.4 to 1.5, preferably 0.4 to 0.8.
The process optionally comprises deprotecting the compound (IIIR) in step c), if P1 is a protecting group, in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and BF3 etherate and a solvent at a temperature in the range from 0 to 40°C.
In another aspect, present invention relates to a process for preparing (S)-Ruxolitinib,

comprising the steps of:
a) reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with D-di-anisoyl tartaric acid of formula D(RA) in presence of a solvent at a temperature in the range from 20-85°C, and forming a mixture of a compound of formula (IIIR) and D-di-anisoyl tartarate salt of formula (IIS) in a ratio of 0.6:0.4 to 0.5:0.5,
, ;
b) separating D-di-anisoyl tartarate salt of formula (IIS) from compound (IIIR) by filtration and obtaining D-di-anisoyl tartarate salt of formula (IIS) in precipitate and the compound (IIIR) in filtrate;
c) reacting the D-di-anisoyl tartarate salt of formula (IIS) obtained in the precipitate with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C to obtain a compound of formula (IIIS)

wherein P1 is selected from H or a protecting group,
and
d) purifying compound (IIIS) in a solvent at a temperature in a range from 50 to 80°C to obtain (S)-Ruxolitinib.
The protecting group is selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
The solvent for purifying compound (IIIS) is selected from the group comprising aprotic solvent, alcoholic solvent, ketonic solvent, ester solvent, etheral solvents, chlorinated solvents, hydrocarbon, and the mixtures thereof. The aprotic solvent is selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent is selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent is selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent is selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon is selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent is selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile or in combination thereof.
The ratio of the D-di-anisoyl tartaric acid of formula D(RA) with respect to racemic compound of formula (II) is 0.4 to 1.5, preferably 0.4 to 0.8.
The process optionally comprises deprotecting the compound (IIIS) obtained in step c), if P1 is a protecting group, in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and BF3 etherate and a solvent at a temperature in the range from 0 to 40°C.

In an aspect, the present invention relates to process comprises optionally converting (R)-Ruxolitinib or (S)-Ruxolitinib to its acid salt by reacting with an acid.

In another aspect, the present invention relates to recovery of (R) or (S) isomer; its racemization and recycling in the process. This improves the overall yield of the process.
In an aspect, the present invention relates to recovery of compound (IIIS) or (IIIR) obtained in the filtrate and racemizing to form racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II). The said process comprises
a) reacting compound (IIIS) or compound (IIIR) with a protecting group in presence of an alkali selected from inorganic base selected from alkali or alkaline earth metal carbonates or bicarbonates or organic base selected from trialkyl amines, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and solvent selected from group comprising polar aprotic solvents such acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof and ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane and mixtures thereof or chlorinated solvent such as dichloromethane;
b) reacting the protected compound (IIIS) or compound (IIIR) with an alkali selected from inorganic base selected from alkali or alkaline earth metal carbonates or bicarbonates, hydroxides or alkoxides or organic base selected from trialkyl amines, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) in presence of a solvent selected from group comprising polar aprotic solvents such acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof and ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane and mixtures thereof or chlorinated solvent such as dichloromethane to obtain a mixture of protected racemic Ruxolitinib and compound of formula (V)
;
c) coupling the above mixture with 3-cyclopentylacrylonitrile

in presence of an alkali selected from inorganic base selected from alkali or alkaline earth metal carbonates or bicarbonates, hydroxides or alkoxides or organic base selected from trialkyl amines, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and a solvent selected from group comprising polar aprotic solvents such acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof and ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane and mixtures thereof or chlorinated solvent such as dichloromethane obtaining protected racemic Ruxolitinib;
d) deprotecting racemic Ruxolitinib in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C to obtain compound of formula (II).
The protecting group is selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.

In another aspect, the present invention relates to the recovery and reuse of chiral resolving agent of formula (RA).

In another aspect, the present invention relates to the process for preparation of resolving agent of formula (RA) by reacting tartaric acid with anisic acid.

In general aspect, the present invention relates to the process for preparation of formula (II).
In one aspect, the present invention provides a process for preparing racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II)

said process comprises;
a) reacting 4-chloro-7H-pyrrolo[2,3-d]pyridine of formula (VIII)

with a protecting group to form compound of formula (VI)
;
b) coupling compound (VI) with 4-pyrazoleboronic acid pinacol ester of formula (VII)

to form compound of formula (V)
;
c) reacting compound of formula (V) with (2E)-3-cyclopentyl-2-propenenitrile
to form protected compound (II); and
d) deprotecting compound (II) in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C.
The protecting group is selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.

In one aspect, the present invention relates to a process for preparing (R)-Ruxolitinib

,
said process comprises the steps of:
a) reacting the racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with L-di-anisoyl tartaric acid of formula L(RA), in presence of a mixture of solvent and water at a temperature in a range from 0 to 60, preferably 50 to 60°C,
,
and forming a mixture of a compound of formula (IIIR) and L-di-anisoyl tartarate salt of formula (2S) in a ratio of 0.6:0.4 to 0.5:0.5,

wherein P1 is selected from H or a protecting group;
b) separating compound (IIIR) from the L-di-anisoyl tartarate salt of formula (2S) by filtration and obtaining the compound (IIIR) in filtrate and L-di-anisoyl tartarate salt (2S) in precipitate;
c) distilling the compound (IIIR) obtained in the filtrate to dryness and degassing under vacuum at temperature 40 to 60 °C to obtain a solid;
d) suspending the solid in a solvent and heating at a temperature of 40 to 60°C and adding L-di-anisoyl tartaric acid of formula L(RA) to obtain a reaction mixture and heating the reaction mixture at a temperature of 50 to 80°C;
e) cooling the reaction mixture at a temperature of 0 to 40°C and directly separating L-di-anisoyl tartarate salt (IIR) by filtration, wherein (IIR) is free from S-Ruxolitinib;
f) reacting the L-di-anisoyl tartarate salt (IIR) with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C to isolate compound of formula (IIIR); and
g) purifying compound (IIIR) in a solvent at a temperature in a range from 50 to 80 °C to obtain (R)-Ruxolitinib.
In an aspect, mixture of solvent and water is taken in a ratio of 1:1 to 1:0.1.
The protecting group is selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
The solvent for purifying compound (IIIR) is selected from the group comprising aprotic solvent, alcoholic solvent, ketonic solvent, ester solvent, etheral solvents, chlorinated solvents, hydrocarbon, and the mixtures thereof. The aprotic solvent is selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent is selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent is selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent is selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon is selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent is selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile or in combination thereof.
The process optionally comprises deprotecting the compound (IIIR), if P1 is a protecting group, in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and BF3 etherate and a solvent at a temperature in the range from 0 to 40°C.

The ratio of the L-di-anisoyl tartaric acid of formula L(RA) with respect to racemic compound of formula (II) is 0.4 to 1.5, preferably 0.4-0.8.
In an aspect, the process comprises optionally converting (R)-Ruxolitinib to its acid salt by reacting with an acid.

Detailed description of the invention
The present invention discloses a process of preparation of chiral Ruxolitinib of formula (I)

by treating Formula (II) with a resolving agent, chiral di-anisoyl tartaric acid of formula (RA). Formula (II) is racemic 3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile i.e. a racemic mixture of R and S forms
, .

Particularly, the invention relates to preparation of chiral Ruxolitinib by separation of (R) and (S) isomers of formula (II).
In an embodiment, the present invention relates to a process for preparing Ruxolitinib of formula (I), said process comprising reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with a resolving agent, di-anisoyl tartaric acid (DATA) of formula (RA), wherein the di-anisoyl tartaric acid (DATA) of formula (RA) is L-di-anisoyl tartaric acid of formula L (RA) for preparing R-Ruxolitinib or D-di-anisoyl tartaric acid of formula D (RA) for preparing S-Ruxolitinib
, .
In this embodiment, ratio of the resolving agent with respect to racemic compound of formula (II) can be 0.4 to 1.8 preferably 0.4 to 0.8.

In an embodiment, the present invention teaches a process for preparation of (R)-Ruxolitinib comprising:
i) reacting compound of formula (II) with L-di-anisoyl tartaric acid of formula L (RA) in the presence or in the absence of a mixture of solvent and water; and
ii) isolating L di-anisoyl tartarate salt (II-R) by filtration followed by reacting with an alkali to form compound of Formula (IIIR), deprotecting compound of Formula (IIIR) to (R)-Ruxolitinib and isolating (R)-Ruxolitinib in the absence of a mixture of solvent and water in step (i)
or
ii) directly isolating (R) Ruxolitinib in the presence of a mixture of solvent and water in step (i).
In one preferred embodiment the present invention teaches a process for preparation of (R)-Ruxolitinib comprising:
i) reacting compound of formula (II) with L-di-anisoyl tartaric acid of formula L (RA);
ii) separating and isolating L di-anisoyl tartarate salt of formula (IIR);
iii) reacting salt of formula (IIR) obtained in stage ii) with suitable alkali to form compound (IIIR);
iv) deprotecting compound of Formula (IIIR) to (R)-Ruxolitinib, if R is a protecting group
v) isolating and purifying compound (IIIR) in a solvent at a temperature in a range from 50 to 80 °C to obtain (R)-Ruxolitinib;
vi) optionally converting (R)-Ruxolitinib to its salt.
In one preferred embodiment, the present invention a process for preparing (R)-Ruxolitinib,

said process comprises the steps of:
a) reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with L-di-anisoyl tartaric acid of formula L(RA), in presence of a solvent at a temperature in a range from 20-85°C,
, ,
and forming a mixture of a compound of formula (IIIS) and L-di-anisoyl tartarate salt of formula (IIR) in a ratio of 0.6:0.4 to 0.5:0.5,
+ ;
b) separating L-di-anisoyl tartarate salt (IIR) from compound (IIIS) by filtration and obtaining the L-di-anisoyl tartarate salt (IIR) in precipitate and compound (IIIS) in filtrate;
c) reacting the L-di-anisoyl tartarate salt (IIR) obtained in the precipitate with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C and isolating compound of formula (IIIR)
;
wherein P1 is selected from H or a protecting group,
and
d) purifying compound (IIIR) in a solvent at a temperature in a range from 50 to 80 °C to obtain (R)-Ruxolitinib.
In this embodiment, ratio of the L-di-anisoyl tartaric acid of formula L(RA) with respect to racemic compound of formula (II) can be 0.4 to 1.5, preferably 0.4 to 0.8.
In this embodiment, the solvent can be selected from the group comprising aprotic solvent selected from acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyltetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably the solvent can be acetonitrile alone or in combination thereof.
In this embodiment, the alkali can be selected from inorganic base selected from group comprising alkali or alkaline earth metal carbonates, bicarbonates, hydroxides or alkoxides; or the alkali can be selected from organic base selected from group comprising trialkyl amines, dimethylaminopyridine, pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and mixtures thereof. The carbonates can be selected from group comprising sodium or potassium or lithium carbonate; bicarbonates are selected from group comprising sodium or potassium or lithium bicarbonates; hydroxides are selected from group comprising sodium or potassium or lithium hydroxides; alkoxides are selected from group comprising sodium methoxide or sodium ethoxide or potassium t-butoxide.
In this embodiment, the protecting group can be selected from group comprising carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
In an embodiment, the present invention relates to optionally deprotecting the isolated compound of formula (IIIR) in step c), if P1 is a protecting group, in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C. The solvent can be selected from the group comprising aprotic solvent selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile alone or in combination thereof.

This preferred embodiment can be schematically represented as shown in scheme 2 below:

Scheme 2

In an embodiment, the present invention relates to a process of optionally converting (R)-Ruxolitinib to its salt by reacting with an acid. The acid can be selected from group comprising maleic acid, phosphoric acid, sulfuric acid, benzoic acid, citric acid, salicylic acid and mixtures thereof, preferably phosphoric acid. Preferably the salt of (R)-Ruxolitinib can be (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile phosphate.
In this preferred embodiment, the process further involves recovery of other compound (IIIS) obtained in the filtrate in step b). The process further involves racemizing compound (IIIS) obtained in the filtrate in step b) to compound (II) and recycling in the reaction.
In this preferred embodiment, the process further involves recovery and reuse of resolving agent L-di-anisoyl tartaric acid of formula L (RA).

In an embodiment, the process further comprises recovery of compound (IIIS) obtained in the filtrate in step b) and racemizing to form racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II). The process comprises,
a) reacting compound (IIIS) obtained in the filtrate in step b) with a protecting group in presence of an alkali and a solvent;
b) reacting the protected compound (IIIS) in step a) with an alkali in presence of a solvent to obtain a mixture of protected racemic Ruxolitinib and compound of formula (V)
;
c) coupling the above mixture with 3-cyclopentylacrylonitrile

in presence of an alkali and a solvent obtaining protected racemic Ruxolitinib obtaining protected racemic Ruxolitinib; and
d) deprotecting racemic Ruxolitinib in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C to obtain compound of formula (II).
In this embodiment, the alkali can be selected from inorganic base selected from alkali or alkaline earth metal carbonates or bicarbonates, hydroxides or alkoxides or organic base selected from trialkyl amines, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and the solvent can be selected from group comprising polar aprotic solvents such acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof and ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane and mixtures thereof or chlorinated solvent such as dichloromethane.
In another embodiment, the present invention teaches a process for preparation of (R)- Ruxolitinib

said process comprising:
i) reacting compound of formula (II) with L-di-anisoyl tartaric acid of formula L (RA) in the mixture of solvent and water;
ii) separating L di-anisoyl tartarate salt (2S) by filtration and obtaining compound (IIIR) in filtrate;
iii) isolating (IIIR) Ruxolitinib from filtrate obtained in stage (ii).
The above process is represented in Scheme 3 below:
Scheme 3
In another embodiment, the present invention relates to a process for preparing (R)-Ruxolitinib,

said process comprising the steps of:
i. reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with L-di-anisoyl tartaric acid of formula L(RA), in presence of a mixture of solvent and water at a temperature in a range from 50 to 60°C,
,
and forming a mixture of a compound of formula (IIIR) and L-di-anisoyl tartarate salt of formula (2S) in a ratio of 0.6:0.4 to 0.5:0.5,

wherein P1 is selected from H or a protecting group;
ii. separating compound (IIIR) from the L-di-anisoyl tartarate salt of formula (2S) by filtration and obtaining the compound (IIIR) in filtrate and L-di-anisoyl tartarate salt (2S) in precipitate;
iii. distilling the compound (IIIR) obtained in the filtrate to dryness and degassing under vacuum at temperature 40 to 60 °C to obtain a solid;
iv. suspending the solid in a solvent selected and heating at a temperature of 40 to 60°C and adding L-di-anisoyl tartaric acid of formula L(RA) to obtain a reaction mixture and heating the reaction mixture at a temperature of 50 to 80°C;
v. cooling the reaction mixture at a temperature of 0 to 40°C and directly separating L-di-anisoyl tartarate salt (IIR) by filtration, wherein (IIR) is free from S-Ruxolitinib;
vi. reacting the L-di-anisoyl tartarate salt (IIR) with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C to isolate compound of formula (IIIR); and
’
wherein P1 is selected from H or a protecting group,
vii. purifying compound (IIIR) in a solvent at a temperature in a range from 50 to 80 °C to obtain (R)-Ruxolitinib.
In this embodiment, mixture of solvent and water can be taken in a ratio of 1:1 to 1:0.1.
In this embodiment, ratio of the L-di-anisoyl tartaric acid of formula L(RA) with respect to racemic compound of formula (II) can be 0.4 to 1.5, preferably 0.4-0.8.
In this embodiment, the process optionally comprises deprotecting the compound (IIIR), if P1 is a protecting group, in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and BF3 etherate and a solvent at a temperature in the range from 0 to 40°C.
In this embodiment, the solvent is selected from the group comprising aprotic solvent selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile or in combination thereof.
In an embodiment, the present invention relates to a process of optionally converting (R)-Ruxolitinib to its salt by reacting with an acid. The acid can be selected from group comprising maleic acid, phosphoric acid, sulfuric acid, benzoic acid, citric acid, salicylic acid and mixtures thereof, preferably phosphoric acid. Preferably the salt of (R)-Ruxolitinib can be (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile phosphate.

In an embodiment, the L di-anisoyl tartarate salt of (2S) obtained in step ii) is converted to free base (S)-Ruxolitinib. In an embodiment, the (S)-Ruxolitinib obtained is racemized to racemic Ruxolitinib. The process for racemization of S-Ruxolitinib to racemic Ruxolitinib comprises,
A] protecting S-Ruxolitinib using a suitable protecting group ‘G’;
B] reacting protected S-Ruxolitinib obtained in stage (A) with suitable alkali to yield mixture of Racemic Ruxolitinib and compound of formula (V);
C] coupling the mixture obtained in stage (B) with 3-cyclopentylacrylonitrile leading to the protected racemic Ruxolitinib; and
D] deprotecting to obtain racemic Ruxolitinib base.

The above process is represented in Scheme 4 below:

Scheme 4
The overall process consists of three stages,
A] Protection: Where the S-Ruxolitinib is protected using a suitable protecting group ‘G’.
B] Racemization and Retro-Michael: Where the protected S-Ruxolitinib is converted to racemic protected Ruxolitinib or the Retro-Michael product (RUP-II) or a mixture of both.
C] Michael addition and Deprotection: Where the product of stage-B is subjected to Michael addition on 3-cyclopentylacrylonitrile leading to the protected racemic-Ruxolitinib. This is followed by deprotection to obtain racemic Ruxolitinib base.

Referring to the reaction scheme 4 where,
G in the reaction scheme= any protecting group which can be selected from 1) carbamates like methyl, ethyl, tert-butyl carbamate, or like. 2) amides like formyl, acetyl, benzoyl, or like. 3) N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl, or like. 4)N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl, or like. 5) N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl, or like. 6) amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl, or like, more preferably N-[2-(trimethylsilyl)ethoxy]methyl derivative.
Solvent 1, 2 & 3 in the reaction scheme can be selected from polar aprotic solvents like DMF, DMSO, acetonitrile and ethers like THF, 1,4-dioxane or halogenated solvents like dichloromethane, or like and mixture of solvents.
Base 1 in the reaction scheme can be selected from inorganic base like alkali or alkaline earth metal carbonates or bicarbonates or can be selected from organic base like trialkyl amines, DBU, DMAP, etc.
Base 2 & 3 in the reaction scheme can be selected from inorganic base like alkali or alkaline earth metal carbonates, bicarbonates, hydroxides or alkoxides. Organic base like trialkyl amines, DBU, DMAP, or like.
Reagent in the reaction scheme can be suitable reagent providing the protecting group ‘G’. Reagent can be selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate).

In an embodiment, the present invention teaches a process for preparation of (S)-Ruxolitinib comprising:
i) reacting compound of formula (II) with D-di-anisoyl tartaric acid of formula D (RA) in the presence or in the absence of a mixture of solvent and water; and
ii) isolating D di-anisoyl tartarate salt (IIS) followed by reacting with an alkali, deprotecting to (S)-Ruxolitinib and isolating (S)-Ruxolitinib in the absence of a mixture of solvent and water in step (i)
or
ii) directly isolating (S) Ruxolitinib in the presence of a mixture of solvent and water in step (i).
In an another preferred embodiment the present invention teaches a process for preparation of (S)-Ruxolitinib comprising:
i) reacting compound of formula (II) with D di-anisoyl tartaric acid of formula D (RA)
ii) separating and isolating D di-anisoyl tartarate salt of formula (IIS);
iii) reacting salt of formula (IIS) formed in stage ii) with suitable alkali to form compound (IIIS);
iv) deprotecting compound (IIIS) to (S)-Ruxolitinib, if R is a protecting group;
v) isolating and purifying compound (IIIS) in a solvent at a temperature in a range from 50 to 80°C to obtain (S)-Ruxolitinib;
vi) optionally converting (S)-Ruxolitinib to its salt.
In an another preferred embodiment, the present invention relates to a process for preparing (S)-Ruxolitinib,

said process comprising the steps of:
a) reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with D-di-anisoyl tartaric acid of formula D(RA) in presence of a solvent at a temperature in the range from 20-85°C,

, ,
and forming a mixture of a compound of formula (IIIR) and D-di-anisoyl tartarate salt of formula (IIS) in a ratio of 0.6:0.4 to 0.5:0.5,
, ;
b) separating D-di-anisoyl tartarate salt of formula (IIS) from compound (IIIR) by filtration and obtaining D-di-anisoyl tartarate salt of formula (IIS) in precipitate and the compound (IIIR) in filtrate;
c) reacting the D-di-anisoyl tartarate salt of formula (IIS) obtained in the precipitate with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C to obtain a compound of formula (IIIS);

wherein P1 is selected from H or a protecting group,
and
d) purifying compound (IIIS) in a solvent at a temperature in a range from 50 to 80°C to obtain (S)-Ruxolitinib.
In this embodiment, the ratio of the D-di-anisoyl tartaric acid of formula D(RA) with respect to racemic compound of formula (II) can be 0.4 to 1.5, preferably 0.4 to 0.8.
In this embodiment, the solvent can be selected from the group comprising aprotic solvent selected from acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyltetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably the solvent can be acetonitrile alone or in combination thereof.
In this embodiment, the alkali can be selected from inorganic base selected from group comprising alkali or alkaline earth metal carbonates, bicarbonates, hydroxides or alkoxides; or the alkali can be selected from organic base selected from group comprising trialkyl amines, dimethylaminopyridine, pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and mixtures thereof. The carbonates can be selected from group comprising sodium or potassium or lithium carbonate; bicarbonates are selected from group comprising sodium or potassium or lithium bicarbonates; hydroxides are selected from group comprising sodium or potassium or lithium hydroxides; alkoxides are selected from group comprising sodium methoxide or sodium ethoxide or potassium t-butoxide.
In this embodiment, the protecting group can be selected from group comprising carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
In an embodiment, the present invention relates to optionally deprotecting the isolated compound of formula (IIIS) in step c), if P1 is a protecting group, in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C. The solvent can be selected from the group comprising aprotic solvent selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile alone or in combination thereof.
This preferred embodiment can be schematically represented as shown in scheme 5 below:

Scheme 5

In an embodiment, the present invention relates to a process of optionally converting (S)-Ruxolitinib to its salt by reacting with an acid. The acid can be selected from group comprising maleic acid, phosphoric acid, sulfuric acid, benzoic acid, citric acid, salicylic acid and mixtures thereof, preferably phosphoric acid. Preferably the salt of (S)-Ruxolitinib can be (3S)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile phosphate.
In this preferred embodiment, the process further involves recovery of compound (IIIR). The process further involves racemizing compound (IIIR) to compound (II) and recycling in the reaction.
In this preferred embodiment, the process further involves recovery and reuse of resolving agent D-di-anisoyl tartaric acid of formula D (RA).

In an embodiment, the process further comprises recovery of compound (IIIR) obtained in the filtrate in step b) and racemizing to form racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II). The process comprises,
a) reacting compound (IIIR) obtained in the filtrate in step b) with a protecting group in presence of an alkali and a solvent;
b) reacting the protected compound (IIIR) in step a) with an alkali in presence of a solvent to obtain a mixture of protected racemic Ruxolitinib and compound of formula (V)
;
c) coupling the above mixture with 3-cyclopentylacrylonitrile

in presence of an alkali and a solvent obtaining protected racemic Ruxolitinib obtaining protected racemic Ruxolitinib; and
d) deprotecting racemic Ruxolitinib in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C to obtain compound of formula (II).
In this embodiment, the alkali can be selected from inorganic base selected from alkali or alkaline earth metal carbonates or bicarbonates, hydroxides or alkoxides or organic base selected from trialkyl amines, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and the solvent can be selected from group comprising polar aprotic solvents such acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof and ethereal solvent can be selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane and mixtures thereof or chlorinated solvent such as dichloromethane.
In an embodiment, the chiral di-anisoyl tartaric acid resolving agent can be selected from (ortho)-di-anisoyl tartaric acid, (meta)-di-anisoyl tartaric acid and (para)-di-anisoyl tartaric acid.
In an embodiment, L-di-anisoyl tartaric acid can be selected from L (ortho)-di-anisoyl tartaric acid, L (meta)-di-anisoyl tartaric acid and L (para)-di-anisoyl tartaric acid.
In an embodiment, D-di-anisoyl tartaric acid can be selected from D(ortho)-di-anisoyl tartaric acid, D(meta)-di-anisoyl tartaric acid and D(para)-di-anisoyl tartaric acid.

In another embodiment, the present invention teaches a process for preparation of compound of formula (II)
.
The process for preparation of compound of formula (II) comprises;
a) reacting 4-chloro-7H-pyrrolo[2,3-d]pyridine of formula (VIII) with suitable protecting agent to form compound of formula (VI);
b) suzuki coupling of compound of formula (VI) with 4-pyrazoleboronic acid pinacol ester of formula (VII) to form compound of formula (V);
r) michael addition of compound of formula (V) and (2E)-3-cyclopentyl-2-propenenitrile to form compound of formula (II);
In an embodiment, the process for preparation of compound of formula (II) comprises step of:
a) reacting 4-chloro-7H-pyrrolo[2,3-d]pyridine of formula (VIII)

with a protecting group to form compound of formula (VI)
;
b) coupling compound (VI) with 4-pyrazoleboronic acid pinacol ester of formula (VII)

to form compound of formula (V)

wherein P1 is H, or a protecting group;
c) reacting compound of formula (V) with (2E)-3-cyclopentyl-2-propenenitrile
to form protected compound (II); and
d) deprotecting compound (II) in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C.
In this embodiment, the protecting group can be selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
In this embodiment, the solvent can be selected from the group comprising aprotic solvent selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile alone or in combination thereof.
The process in this embodiment, is represented in Scheme 6 below:

Scheme 6
In another embodiment the present invention teaches the process for preparation of chiral resolving agent (RA) comprising reacting anisic acid with chiral tartaric acid.
, .
Chiral di-anisoyl tartaric acid resolving agent can be selected from (ortho)-di-anisoyl tartaric acid, (meta)-di-anisoyl tartaric acid and (para)-di-anisoyl tartaric acid.

L-di-anisoyl tartaric acid (L-DATA) can be selected from L-(ortho)-di-anisoyl tartaric acid, L-(meta)-di-anisoyl tartaric acid and L-(para)-di-anisoyl tartaric acid.
D-di-anisoyl tartaric acid (D-DATA) can be selected from D (ortho)-di-anisoyl tartaric acid, D (meta)-di-anisoyl tartaric acid and D (para)-di-anisoyl tartaric acid.

In an embodiment, the resolving agent used in the present invention for resolving R-Ruxolitinib is L-di-anisoyl tartaric acid (L-DATA) i.e. (2R,3R)-2,3-bis[(4-methoxybenzoyl)oxy]butanedioic acid (Synonyms: Di-p-methoxybenzoyl L-tartaric acid) of formula L (RA). It is synthesized from L(+)-tartataric acid which is a naturally occurring form of tartaric acid and is cheaper than it’s enantiomer D-tartaric acid. L-DATA is levorotatory which contradicts to the other resolving agents mentioned in prior art, which are dextrorotatory. It effectively resolves the racemic mixture of formula (II) to selectively yield salt of R-isomer.

The present invention involves recovery of other isomers, its racemization and recycling, thus improving the overall yield of the process making the process substantially cost-effective. The present invention also involves recovery and reuse of the chiral resolving agent of formula (RA).
The present process avoids lengthy steps of purification thus avoids use of large amount of solvents required for purification thereby making the process industrially feasible, ultimately avoiding yield loss and making the process substantially cost-effective and providing the product with high optical purity. Surprisingly the process of the present invention in view of the prior art process involves only one step for purification and has improved and better overall yield of Ruxolitinib.

EXAMPLES
The following examples illustrate the invention, but are not limiting thereof.
Example 1
Preparation of 4-chloro-7-[2-(trimethylsilyl)ethoxy]methyl-7H-pyrrolo[2,3-d]pyrimidine (Formula VI).
Potassium carbonate (677 gm) was added to the solution of 4-chloro-7H-pyrrolo[2,3-d]pyridine of formula (VIII) (300 gm) in DMF (900 ml) with stirring. The reaction mixture heated to 40°C-45°C for 3 hours. The reaction mixture was then cooled to 20°C - 25°C and 2-(trimethylsilyl)ethoxymethyl chloride (677 gm) was added slowly. The reaction mixture was stirred for 5 hours.
Toluene (1800 ml) and water (3000 ml) was added to the reaction mass and stirred for 30 minutes. The layers were separated and toluene (1200 ml) was added to the aqueous layer. The mixture was stirred thoroughly. The layers were separated and the combined toluene layer was washed with 30% potassium carbonate aqueous solution (1200 ml) followed by water (600 ml X 2 times) and brine (1200 ml). The solvent was distilled off under vacuum to obtain an oil.
n-Heptane (900 ml) was charged to the oil and the mixture was stirred at -20°C to -30°C for 30 minutes. The solution was filtered at -20°C and washed with n-heptane (150 ml). The solid was dissolved in dichloromethane and further concentrated to obtain 4-chloro-7-[2-(trimethylsilyl)ethoxy]methyl-7H-pyrrolo[2,3-d]pyrimidine (350 gm) of formula (VI) in the form of oil.
LCMS: Purity = 97.75%

Example 2
Preparation of 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine (Formula V).
The solution of 4-pyrazoleboronic acid pinacol ester (47.9 gm) of formula (VII) in IPA (500 ml) was charged to 4-chloro-7-[2-(trimethylsilyl)ethoxy]methyl-7H-pyrrolo[2,3-d]pyrimidine (50 gm) of formula (VI). The solution of potassium carbonate (36.44 gm) in 125 ml water was charged to the above mixture. The mixture was purged with argon for two hours and tertakis(triphenylphosphine)palladium (0) (7.5 gm) was added. The reaction mixture was stirred at 80-85°C for 6-7 hours.
The reaction mixture was cooled to room temperature and filtered. The filtrate was distilled under vacuum to obtain an oil. Ethyl acetate (600 ml) and water (300 ml) was added to the oil and stirred. The organic layer was washed with water (300 ml) and distilled off under vacuum to obtain crude product. The crude product was purified using methyl tert-butyl ether (MTBE) and dried to obtain 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine (43.4 gm) of formula (V).
Purity by HPLC = 98.67%.

Example 3
Synthesis of 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine (Formula V).
Potassium carbonate (225 gm) was charged to the stirred solution of 4-chloro-7H-pyrrolo[2,3-d]pyridine (100 gm) of formula (VIII) in DMF (300 ml) and reaction mixture heated to 40°C to 45°C for 2.5 hours. The reaction mixture was cooled to 20°C - 25°C and 2-(trimethylsilyl)ethoxymethyl chloride (185 gm) was added slowly. The reaction mixture was stirred for 4 hours. Toluene (500 ml) and water (1000 ml) was added to reaction mixture and stirred for 30-60 minutes. The layers were separated and aqueous layer was back extracted with toluene 400 ml. Combined toluene layer was washed with 30% potassium carbonate aqueous solution (400 ml) followed by water (400 ml X 2 times) and brine (400 ml). The solvent was distilled off under vacuum to obtain an oil (241 gm).
Ethanol (1500 ml) was added to the oil obtained above and 4-pyrazoleboronic acid pinacol ester (177 gm) of formula (VII) was charged to the solution with stirring. The mixture was treated with charcoal, filtered and mixed with a pre-charcoalized solution of potassium carbonate (270 gm) in water (800 ml). The reaction mixture was purged with nitrogen for two hours and then tertakis(triphenylphosphine)palladium (0) (15 gm) was added. The reaction mixture was stirred at 78-80°C.
After completion of the reaction, the reaction mixture was filtered and cooled to room temperature. Water (3700 ml) was added slowly to the reaction mixture with stirring over a period of 1.5 to 2 hours. The obtained crude product was filtered and dried under vacuum at 45-50°C. MTBE (370 ml) was charged to the dried product and stirred. The mixture was filtered and washed with MTBE (90 ml x 2) and dried to obtain 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine (153.8 gm) of formula (V).
Purity = 98.75%

Example 4
Preparation of (3R/S)-cyclopentyl-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (Formula II).
Potassium carbonate (21.8 gm) was added to a suspension of 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine (100 gm) of formula (V) in acetonitrile (500 ml) at room temperature. (EZ)-3-cyclopentylacrylonitrile (65.30 gm) was added to the reaction mixture and heated at 70°C to 80°C for 7 hours. The mass was cooled to room temperature and filtered. The filtrate was distilled off under vacuum to obtain an oil. The oil was dissolved in dichloromethane (600 ml) and washed with water (600mlx2). The solvent was evaporated under vacuum to give 3-cyclopentyl-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (156 gm) as an oil.

Example 5
Preparation of (3R/S)-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (Formula II).
Borontrifluoride etherate (112.64 gm) was charged to the solution of 3-cyclopentyl-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (156 gm) in acetonitrile (800 ml) at 5-15°C. The reaction mixture was stirred at 20-25°C for 4 hours. The reaction mixture was further cooled to 5-15°C and water (200 ml) was added. The reaction mixture was warmed to 20-25°C and stirred at this temperature for 45-60 minutes. The reaction mixture was cooled to 5-15°C and aqueous ammonia solution (190 ml) was added. The reaction mixture was warmed to 20-25°C and stirred at this temperature for 1-2 hours. To this reaction mixture was added 20% aqueous sodium chloride solution (500 ml) and ethyl acetate (500 ml), stirred for 30-45 minutes. The layers were separated and aqueous layer was again extracted with ethyl acetate (300 ml). The combined ethyl acetate layer was washed with sodium bicarbonate solution followed by water. The ethyl acetate layer was treated with activated carbon and distilled off under vacuum. MDC (150 ml) was charged to the residue obtained and stirred at room temperature for 30 minutes. To the obtained slurry was added n-heptane (300 ml) and heated at 35-40°C for 30-45 minutes. The slurry was then cooled to 15-20°C, filtered and washed with n-heptane (276 ml). The wet product was dried under vacuum at 45-50°C to yield 3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (81.8 gm).
LCMS: Purity = 98.11%

Example 6
Preparation of of (2R,3R)-2,3-bis[(4-methoxybenzoyl)oxy]butanedioic acid (Synonyms: Di-p-methoxybenzoyl L-tartaric acid).
Under nitrogen atmosphere thionyl chloride (504 ml) was charged 4-methoxybenzoic acid (153 gm) and reaction mixture heated to 70-72°C under stirring to obtain a clear solution. Dimethyl formamide (0.5 ml) was added to the reaction mixture. The reaction mixture was stirred at 65-75°C for 2.5 hours. The excess thionyl chloride was removed by distillation. Toluene (100 ml) was added to the reaction mixture and distilled off under vacuum to obtain 4-methoxybenzoylchloride as oil.
L-tartaric acid (50 gm) was charged to the reaction mixture and heated to 100-120°C. The reaction mixture was stirred for 4 hours at 100-120°C and cooled to 80-90°C followed by addition of water (80 ml). The reaction mixture was further cooled to 50-65°C and acetone (500 ml) was added. The reaction mixture was then gradually cooled to room temperature. The reaction mixture was further cooled to 5-10°C and stirred for 30 minutes. The mixture was filtered and 4-methoxybenzoic acid (46 gm, wet) was recovered by filtration. The filtrate was concentrated under vacuum and acetone (130 ml) was added to it at 25-30°C. The reaction mixture was stirred at this temperature and filtered to recover 4-methoxybenzoic acid (7 gm, wet).
Acetone (200 ml) and charcoal (2 gm) was added to the filtrate and stirred at room temperature and filtered. The filtrate was distilled off under vacuum to obtain crude L-DATA (L-(RA) (167 gm). Toluene (600 ml) was added to the crude product and stirred at 80-90°C for 45 minutes followed by filtration at 70-90°C. The cake was washed with toluene (400 ml) and dried under vacuum at 45-50°C to obtain solid (111 gm). This solid was stirred with dichloromethane for 3-4 hours, filtered and washed with dichloromethane. The material was dried under vacuum to yield L-DATA (L-(RA)) (208.4 gm).
Purity = 98.05%, LCMS [M-1] = 417.31
1H NMR (DMSO-D6, 300 MHz): 7.995-7.905 (dd, 4H), 7.144-7.069 (dd, 4H), 5.819 (s, 2H), 3.857 (s, 6H).
13C NMR (DMSO-D6): 167.87, 164.79, 164.21, 132.10, 121.11, 114.81, 71.70, 56.09.
Specific Optical Rotation: 1% in ethanol at 22°C, 589nm = -161.85°
Specific Optical Rotation: 1% in acetone at 22°C, 589nm = -156.72°

Example 7
Preparation of (2R,3R)-2,3-bis[(4-methoxybenzoyl)oxy]butanedioic acid-(3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (1:1) (Formula IIR) and Isolation of (Formula IIR).
To acetonitrile (1200 ml) was added racemic Ruxolitinib (3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile) (80 gm) and reaction mixture heated to 50-60°C. L-DATA (54.62 gm) was charged and reaction mixture was stirred at 50-60°C for 30-45 minutes. The reaction mixture was then gradually cooled to room temperature and stirred for 30-45 minutes. The reaction mixture was again heated to 65-80°C and stirred at that temperature for 30-45 minutes. The reaction mixture was cooled gradually to 25-30°C and stirred at 25-30°C for 2-3 hours, filtered and washed with acetonitrile (240 ml). The product was dried under vacuum at 45-55°C to obtain Ruxolitinib-L-DATA salt enriched in R-Ruxolitinib (84 gm, Chiral purity = 94.74%).
The obtained solid (84 gm), was suspended in acetonitrile (1680 ml) and heated to 65-75°C. Methanol (83.4 ml) was added to the reaction mixture and stirred at 65-75°C for 15-45 minutes. The reaction mixture was then gradually cooled to 25-30°C and stirred at this temperature for 2 hours. The resultant solid was then filtered, washed with acetonitrile (252 ml) and dried under vacuum to yield Ruxolitinib-L-DATA salt, substantially enriched in R-Ruxolitinib (59.6 gm, Chiral purity = 99.87%).
The filtrate MLR was kept aside for recovery of (S)-isomer and racemization.
Reference: Scheme 2

Example 8
Synthesis of (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (Formula (III R) and Purification of IIIR to R-Ruxolitinib).
A suspension of (2R,3R)-2,3-bis[(4-methoxybenzoyl)oxy]butanedioic acid-(3R)-3--cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (1:1), (9.5 gm) in ethyl acetate (70 ml) was stirred at 20-30°C.
The pH of the mixture was adjusted to 8.5-11.0 by using sodium carbonate solution. The biphasic reaction mixture was then stirred at 20-30°C for 30 minutes and the layers were separated. The aqueous layer was back extracted using ethyl acetate (50 ml). Combined ethyl acetate layer was washed with water (25 ml) and distilled off under vacuum at 40-45°C to give (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (4 gm).
The Aqueous layer was kept aside for recovery of L-DATA.
Reference: Scheme 2

Example 9
Preparation of (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile phosphate (Salt of Ruxolitinib).
Ruxolitinib base (4 gm), obtained in example 8, was dissolved in isopropanol (45 ml) by heating to 50-55°C. Phosphoric acid (85%, 1.73 gm) in isopropanol (5 ml) at 50-55°C was charged. The reaction mixture was stirred at 50-55°C for 1 hour and then gradually cooled to 25-30°C. The reaction mixture was then stirred at 25-30°C for 2-3 hours, filtered, washed with isopropanol (10 ml) and dried under vacuum at 50-55°C to obtain Ruxolitinib phosphate (4.4 gm).
HPLC Purity = 99.80%, [M+1] = 307.12,
Chiral purity = 99.95%

Example 10
Recovery of S-Ruxolitinib and racemization to obtain racemic 3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (Formula II).
Part A: Recovery of enriched S-Ruxolitinib
The filtrate MLR from example 7 was distilled under vacuum to obtain a solid (57 gm). Ethyl acetate (345 ml) and water (285 ml) was charged to the solid and stirred at 20-30°C. The pH of this mixture was adjusted to 9.5-10.0 using 10% sodium carbonate solution in water. The ethyl acetate layer was then separated and aqueous layer was back extracted with ethyl acetate (120 mlx2). The combined ethyl acetate layer was washed with water (170 ml) followed by brine (170 ml) and distilled off under vacuum. The obtained residue (44.8 gm) was dissolved in dichloromethane and precipitated by addition of n-heptane. The suspension was filtered and dried to yield a solid enriched in S-Ruxolitinib (41 gm).
Part B: Protection (formation of compound of Formula IIIS)
The solid obtained in part A (40 gm) was dissolved in 1,4-dioxane (1200 ml) and stirred at 25-30°C. Triethylamine (40 gm), BOC-anhydride (28.5 gm) and DMAP (3.2 gm) was charged to the mixture. The reaction mixture was stirred at 25-30°C for 1.5 to 2 hours. After completion of reaction, water (1000 ml) followed by ethyl acetate (750 ml) was added and stirred.
The layers were separated and the aqueous layer was extracted with ethyl acetate (250 ml X 2 times). The combined organic layer was washed with water (500 ml), followed by 10% ammonium chloride solution (200 ml) and again water (250 ml). The organic layer was then distilled under vacuum at 40-50°C to obtain a residue. MTBE (100 ml) was added to the residue and evaporated under vacuum to give the N-BOC-(S)-Ruxolitinib (Formula IIIS).
Part C: Racemization (formation of compound of Formula II).
The solid obtained in part B, (0.5 gm) was dissolved in THF (15 ml) and potassium tert-butoxide (0.14 gm) was charged. The reaction mixture was stirred at 55-60°C for 24 hours and then filtered. The filtrate was evaporated under vacuum and partitioned between ethyl acetate and water. The ethyl acetate layer was distilled of under vacuum to give racemic N-BOC-Ruxolitinib (0.3 gm).
Part D: Deprotection
The solid obtained in part C (0.2 gm) was dissolved in methanol (1 ml) and stirred at 25-30°C. To this solution was added a solution of HCl in water (1:9) (0.25 ml). The reaction mixture was stirred at room temperature until completion of reaction after which the pH of reaction mixture was adjusted to 7-8 using dilute sodium hydroxide solution. The precipitated solid was filtered and dried under vacuum at 45-50°C to yield racemic Ruxolitinib (Formula II) (1.4 gm).
Reference: Scheme 2

Example 11
Synthesis of (2R,3R)-2,3-bis[(4-methoxybenzoyl)oxy]butanedioic acid-(3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (1:1) (Formula IIS)
To acetonitrile (15 ml) was added racemic Ruxolitinib (3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile) (5 gm) and water (5 ml, 1V) and reaction mixture heated to 50-60°C. To this was added L-DATA (3.41 gm) and reaction mixture stirred at 50-60°C for 30-45 minutes. The reaction mixture was then gradually cooled to room temperature and stirred for 30-45 minutes. The reaction mixture was again heated to 65-80°C and stirred at that temperature for 30-45 minutes. After this the reaction mixture was cooled gradually to 25-30°C and stirred at 25-30°C for 2-3 hours, filtered and washed with acetonitrile (15 ml). The product was dried under vacuum at 45-55°C to obtain S-Ruxolitinib-L-DATA salt enriched in S-Ruxolitinib (5 gm, S-Ruxolitinib = 95.59%).The mother liquor (MLR) was then distilled to dryness and degassed under vacuum at 40-60°C to obtain a solid. The obtained solid, was suspended in acetonitrile and reaction mixture heated to 50-60°C. To this was added L-DATA (0.45 mol.eq.) and reaction mixture stirred at 50-60°C for 30-45 minutes. The reaction mixture was then gradually cooled to room temperature and stirred for 30-45 minutes. The reaction mixture was again heated to 65-80°C and stirred at that temperature for 30-45 minutes. After this the reaction mixture was cooled gradually to 25-30°C and stirred at 25-30°C for 2-3 hours, filtered and washed with acetonitrile. The product was dried under vacuum at 45-55°C to obtain R-Ruxolitinib-L-DATA salt with sufficiently enhanced chiral purity suitable for conversion to R-Ruxolitinib Phosphate salt.
Reference: Scheme 3

Example 12
Racemization of (S)-Ruxolitinib
Stage A] Protection
Example A.1(using DMF/NaHCO3): To 10 gm solid enriched in S-Ruxolitinib (S-Ruxolitinib = 80.01% by chiral HPLC), was charged DMF (60 ml) at room temperature and stirred to obtain a solution. To this was added sodium bicarbonate (6.85 gm) and reaction mixture cooled to 0-10°C. To the reaction mixture was added 2-(trimethylsilyl)ethoxymethyl chloride (11.6 gm) and the temperature of reaction mixture was gradually raised to 25-30°C. The reaction mixture was stirred at this temperature until TLC indicated complete product formation. After completion of reaction, the reaction mixture was cooled to 20-25°C and water (100 ml) added followed by addition of ethyl acetate (80 ml). The reaction mixture was stirred, settled and layers separated. The aqueous layer was back extracted with ethyl acetate and combined ethyl acetate layer was washed with water followed by brine. The ethyl acetate layer was dried over anhydrous sodium sulfate and distilled to obtain 3-(S)-3-cyclopentyl-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (19.9 gm) which was used in next stage as such.
Purity = 95.35%
LCMS [M+1] = 437.43
Example A.2 (using MDC/DIPEA): To 1 gm solid enriched in S-Ruxolitinib (S-Ruxolitinib = 80.01% by chiral HPLC), was charged dichloromethane (10 ml) at room temperature and stirred. To this was added N,N-diisopropylethylamine (DIPEA) (0.5 gm) at 0-10°C. To the reaction mixture was added 2-(trimethylsilyl)ethoxymethyl chloride (0.41 gm) and the reaction mixture was stirred at 0-10°C until TLC indicated complete product formation. After completion of reaction, the reaction mixture was gradually warmed to 20-30°C and water (20 ml) added. The reaction mixture was stirred, settled and layers separated. The aqueous layer was back extracted with dichloromethane and combined organic layer was washed with water followed by saturated ammonium chloride solution. The organic layer was dried over anhydrous sodium sulfate and distilled to obtain 3-(S)-3-cyclopentyl-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile (0.7 gm) which was used in next stage as such.
Purity = 98.93%
LCMS [M+1] = 437.50
Stage B] Racemization and Retro-Michael:
Example B: To 5 gm of oil (obtained in example A.1), was added acetonitrile (12.5 ml) and potassium tert-butoxide (0.92 gm) and reaction mixture heated at 60-70°C for about 15 to 25 hours. After this the solvent was removed under vacuum to obtain an oily semi-solid mass. To this was added water (20 ml) and ethyl acetate (20 ml) and reaction mixture stirred for 5-10 minutes. The reaction mixture was settled and layers separated. The aqueous layer was back extracted with ethyl acetate and combined organic layer was washed with saturated ammonium chloride solution followed by water. The organic layer was dried over anhydrous sodium sulfate, filtered and distilled to obtain an oil (6 gm). Analysis by LCMS indicated a mixture of 3-(RS)-3-cyclopentyl-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile and 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine.
LCMS:
[M+1] = 437.47, 73.98% 3-(RS)-3-cyclopentyl-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile &
[M+1] = 316.36, 24.05% 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine.
Stage C] Michael Addition and Deprotection:
Example C: To 6 gm of oil (obtained in example B), was added acetonitrile (12.5 ml), powdered potassium carbonate (0.56 gm) and 3-cyclopentylacrylonitrile (1.2 gm). The reaction mixture was then stirred at 65-70°C for 15-20 hours after which TLC indicated completion of Michael addition reaction. The reaction mixture was then cooled and filtered. The filtrate was concentrated under vacuum to dryness and then stirred in a mixture of dichloromethane (30 ml) and water (30 ml). The organic layer was separated and washed with brine, dried over sodium sulfate and solvent evaporated under vacuum to obtain oil (5.8 gm). This oil was dissolved in acetonitrile (25 ml) and cooled to 0-5°C. BF3.Etherate (3.3 gm) was slowly added to the reaction mixture at this temperature and the temperature of reaction mixture was raised to 20-25°C gradually. The reaction mixture was stirred at 20-25°C till TLC indicated completion of deprotection reaction. Reaction mixture was cooled to 0-5°C and water (10 ml) was added. The reaction mixture was warmed to 20-25°C and stirred at this temperature for about 30 minutes. The reaction mixture was again cooled to 0-5°C and ammonia solution (6 ml) diluted with water (10 ml) was added. The reaction mixture was warmed to 20-25°C and stirred at this temperature for two hours. To this was then added brine solution (10 ml) followed by ethyl acetate (10 ml). The reaction mixture was stirred, settled and organic layer separated. The aqueous layer was back extracted with ethyl acetate (10 ml) and combined organic layer was washed with 1M sodium bicarbonate solution (10 ml) followed by hot water (10 ml, twice). The organic layer was treated with carbon, filtered and solvent evaporated under vacuum to obtain racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile as solid.
Chiral HPLC:
R-Ruxolitinib = 49.54%
S-Ruxolitinib = 50.46%
Reference: Scheme 4

Example 13
Example 13 (A-1) - Preparation of Di-p-anisoyl-D-Tartarate:
In a 250 ml RBF, charged D-tartaric acid (10 gm) and p-anisoyl chloride (27 ml) and heated the reaction mixture to 120°C. After maintaining the reaction mixture at 120°C for 3 hours, the heating was stopped and reaction mixture was cooled to room temperature, gradually. To the obtained solid was charged diisopropyl ether (150 ml) and again stirred the reaction mixture at 60-70°C. The solid was isolated by filtration after cooling to room temperature. The solid was then dissolved in acetone (200 ml) to give a clear solution. Water 26 ml) was added to this solution and resultant mixture evaporated under vacuum at 45-50°C. To the residue was charged dichloromethane (80 ml) and stirred at about 40°C for 10-20 minutes. The reaction mixture was cooled to room temperature and filtered, washed with additional dichloromethane (50 ml). The obtained solid was dried under vacuum to obtain Di-p-anisoyl-D-Tartarate (27.5 gm). The product was confirmed by LCMS.
Example 13 (A-2) - Preparation of S-Ruxolitinib-D-DATA salt:
A mixture of racemic ruxolitinib (5 gm) in acetonitrile (75 ml) was heated to 52-58°C. To this reaction mixture was charged Di-p-anisoyl-D-Tartarate (3.41 gm, prepared as described above). Salt precipitation was observed at 55-58°C after about 20 minutes. The reaction mass was stirred at same temperature for additional 30 minutes and then gradually cooled to room temperature. The reaction mixture was again heated to about 72-80°C and then gradually cooled to room temperature. The obtained solid was filtered and washed with chilled acetonitrile (10 ml). The solid was dried under vacuum at 45°C to give S-Ruxolitinib-D-DATA salt (3.6 gm).
Chiral purity: S-Isomer = 94.65%.

The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to a person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.
,CLAIMS:
1. A process for preparing Ruxolitinib of formula (I)
,
said process comprising reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with a resolving agent, di-anisoyl tartaric acid (DATA) of formula (RA),
, ,
wherein P1 is selected from H or a protecting group,
wherein the di-anisoyl tartaric acid (DATA) of formula (RA) is L-di-anisoyl tartaric acid of formula L (RA) for preparing R-Ruxolitinib or D-di-anisoyl tartaric acid of formula D (RA) for preparing S-Ruxolitinib
, .

2. The process as claimed in claim 1, wherein ratio of the resolving agent with respect to racemic compound of formula (II) is 0.4 to 1.8 preferably 0.4 to 0.8.
3. A process for preparing (R)-Ruxolitinib,

comprising the steps of:
a) reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with L-di-anisoyl tartaric acid of formula L(RA), in presence of a solvent at a temperature in a range from 20-85°C,
, ,
and forming a mixture of a compound of formula (IIIS) and L-di-anisoyl tartarate salt of formula (IIR) in a ratio of 0.6:0.4 to 0.5:0.5,
+ ;
b) separating L-di-anisoyl tartarate salt (IIR) from compound (IIIS) by filtration and obtaining the L-di-anisoyl tartarate salt (IIR) in precipitate and compound (IIIS) in filtrate;
c) reacting the L-di-anisoyl tartarate salt (IIR) obtained in the precipitate with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C and isolating compound of formula (IIIR)
’
wherein P1 is selected from H or a protecting group,
and
d) purifying compound (IIIR) in a solvent at a temperature in a range from 50 to 80 °C to obtain (R)-Ruxolitinib.
4. The process as claimed in claim 3, wherein ratio of the L-di-anisoyl tartaric acid of formula L(RA) with respect to racemic compound of formula (II) is 0.4 to 1.5, preferably 0.4 to 0.8.
5. A process for preparing (S)-Ruxolitinib,

comprising the steps of:
a) reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with D-di-anisoyl tartaric acid of formula D(RA) in presence of a solvent at a temperature in the range from 20-85°C,
, ,
and forming a mixture of a compound of formula (IIIR) and D-di-anisoyl tartarate salt of formula (IIS) in a ratio of 0.6:0.4 to 0.5:0.5,
, ;
b) separating D-di-anisoyl tartarate salt of formula (IIS) from compound (IIIR) by filtration and obtaining D-di-anisoyl tartarate salt of formula (IIS) in precipitate and the compound (IIIR) in filtrate;
c) reacting the D-di-anisoyl tartarate salt of formula (IIS) obtained in the precipitate with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C to obtain a compound of formula (IIIS)

wherein P1 is selected from H or a protecting group,
and
d) purifying compound (IIIS) in a solvent at a temperature in a range from 50 to 80°C to obtain (S)-Ruxolitinib.
6. The process as claimed in claim 5, wherein ratio of the D-di-anisoyl tartaric acid of formula D(RA) with respect to racemic compound of formula (II) is 0.4 to 1.5, preferably 0.4 to 0.8.
7. The process as claimed in claims 3 and 5, wherein process comprises optionally converting (R)-Ruxolitinib or (S)-Ruxolitinib to its acid salt by reacting with an acid.
8. The process as claimed in claim 11, wherein the acid is selected from group comprising maleic acid, phosphoric acid, sulfuric acid, benzoic acid, citric acid, salicylic acid and mixtures thereof.
9. The process as claimed in claims 3 and 5, wherein the solvent is from the group comprising aprotic solvent selected from acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyltetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably solvent is acetonitrile alone or in combination thereof.
10. The process as claimed in claims 3 and 5, wherein the alkali in step c) is selected from inorganic base selected from group comprising alkali or alkaline earth metal carbonates, bicarbonates, hydroxides or alkoxides; or the alkali in step c) is selected from organic base selected from group comprising trialkyl amines, dimethylaminopyridine, pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and mixtures thereof.
11. The process as claimed in claim 10, wherein the carbonates are selected from group comprising sodium or potassium or lithium carbonate; bicarbonates are selected from group comprising sodium or potassium or lithium bicarbonates; hydroxides are selected from group comprising sodium or potassium or lithium hydroxides; alkoxides are selected from group comprising sodium methoxide or sodium ethoxide or potassium t-butoxide.
12. The process as claimed in claims 1, 3 and 5, wherein the protecting group is selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
13. The process as claimed in claims 3 and 5, wherein the process optionally comprises deprotecting the obtained compound (IIIR) or (IIIS) in step c), if P1 is a protecting group in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C.
14. The process as claimed in claim 13, wherein the solvent is selected from the group comprising aprotic solvent selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile alone or in combination thereof.
15. The process as claimed in claim 3 and 5, wherein said process further comprises recovery of compound (IIIS) or compound (IIIR) obtained in the filtrate in step b) and racemizing to form racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II).
16. The process as claimed in claim 15, wherein said process comprises:
a) reacting compound (IIIS) or compound (IIIR) obtained in the filtrate in step b) with a protecting group in presence of an alkali and a solvent;
b) reacting the protected compound (IIIS) or compound (IIIR) in step a) with an alkali in presence of a solvent to obtain a mixture of protected racemic Ruxolitinib and compound of formula (V)

wherein P1 is selected from H or a protecting group;
c) coupling the above mixture with 3-cyclopentylacrylonitrile

in presence of an alkali and a solvent obtaining protected racemic Ruxolitinib obtaining protected racemic Ruxolitinib;
d) deprotecting racemic Ruxolitinib in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C to obtain compound of formula (II).
17. The process as claimed in claim 16, wherein the alkali is selected from inorganic base selected from alkali or alkaline earth metal carbonates or bicarbonates, hydroxides or alkoxides or organic base selected from trialkyl amines, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 4-dimethylaminopyridine (DMAP) and the solvent is selected from group comprising polar aprotic solvents such acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof and ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane and mixtures thereof or chlorinated solvent such as dichloromethane.
18. A process for preparing racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II)

said process comprises;
a) reacting 4-chloro-7H-pyrrolo[2,3-d]pyridine of formula (VIII)

with a protecting group to form compound of formula (VI)
;
b) coupling compound (VI) with 4-pyrazoleboronic acid pinacol ester of formula (VII)

to form compound of formula (V)
;
c) reacting compound of formula (V) with (2E)-3-cyclopentyl-2-propenenitrile
to form protected compound (II); and
d) deprotecting compound (II) in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and boron trifluoride diethyl etherate (BF3 etherate) and a solvent at a temperature in the range from 0 to 40°C.
19. The process as claimed in claims 16 and 18, wherein the protecting group is selected from carbamates like methyl, ethyl, tert-butyl carbamate; amides like formyl, acetyl, benzoyl; N-sulfonyl derivatives like N-benzenesulfonyl, N-p-toluenesulfonyl, N-methanesulfonyl; N-alkyl/aryl derivatives like N-vinyl, N-2-chloroethyl; N-trialkylsilyl derivatives like N-t-butyldimethylsilyl, N-triisopropylsilyl; amino acetal derivatives like N-hydroxymethyl, N-methoxymethyl, N-(2-chloroethoxy)methyl, N-[2-(trimethylsilyl)ethoxy]methyl; preferably protecting group is N-[2-(trimethylsilyl)ethoxy]methyl derivative.
20. The process as claimed in claims 16 and 18, wherein the solvent is selected from the group comprising aprotic solvent selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile alone or in combination thereof.
21. A process for preparing (R)-Ruxolitinib,

said process comprising the steps of:
a) reacting racemic 3-(RS)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile of formula (II) with L-di-anisoyl tartaric acid of formula L(RA), in presence of a mixture of solvent and water at a temperature in a range from 50 to 60°C,
,
and forming a mixture of a compound of formula (IIIR) and L-di-anisoyl tartarate salt of formula (2S) in a ratio of 0.6:0.4 to 0.5:0.5,

wherein P1 is selected from H or a protecting group;
b) separating compound (IIIR) from the L-di-anisoyl tartarate salt of formula (2S) by filtration and obtaining the compound (IIIR) in filtrate and L-di-anisoyl tartarate salt (2S) in precipitate;
c) distilling the compound (IIIR) obtained in the filtrate to dryness and degassing under vacuum at temperature 40 to 60 °C to obtain a solid;
d) suspending the solid in a solvent selected and heating at a temperature of 40 to 60°C and adding L-di-anisoyl tartaric acid of formula L(RA) to obtain a reaction mixture and heating the reaction mixture at a temperature of 50 to 80°C;
e) cooling the reaction mixture at a temperature of 0 to 40°C and directly separating L-di-anisoyl tartarate salt (IIR) by filtration, wherein (IIR) is free from S-Ruxolitinib;
f) reacting the L-di-anisoyl tartarate salt (IIR) with an alkali selected from inorganic base and organic base and a solvent at a temperature in the range from 0 to 60°C to isolate compound of formula (IIIR); and
’
wherein P1 is selected from H or a protecting group,
g) purifying compound (IIIR) in a solvent at a temperature in a range from 50 to 80 °C to obtain (R)-Ruxolitinib.
22. The process as claimed in claim 21, wherein mixture of solvent and water is taken in a ratio of 1:1 to 1:0.1.
23. The process as claimed in claim 21, wherein ratio of the L-di-anisoyl tartaric acid of formula L(RA) with respect to racemic compound of formula (II) is 0.4 to 1.5, preferably 0.4-0.8.
24. The process as claimed in claim 21, wherein the process comprises optionally deprotecting the compound (IIIR), if P1 is a protecting group in presence of a reagent selected from lithium tetrafluoroborate, trifluoroacetic acid and BF3 etherate and a solvent at a temperature in the range from 0 to 40°C.
25. The process as claimed in claims 21 and 24, wherein the solvent is selected from the group comprising aprotic solvent selected from the group comprising acetonitrile, dimethyl formamide (DMF), dimethyl sulphoxide (DMSO) and mixtures thereof; alcoholic solvent selected from the group comprising methanol, ethanol, isopropyl alcohol (IPA) and mixtures thereof; ketonic solvent selected from the group comprising acetone, methyl isobutyl ketone (MIBK) and mixtures thereof; ester solvent selected from the group comprising ethyl acetate, isopropyl acetate; ethereal solvent is selected from the group comprising tetrahydrofuran (THF), 1,4-dioxane, 2-methyl tetrahydrofuran and mixtures thereof; hydrocarbon selected from the group comprising cyclohexane, hexane, toluene, chlorinated solvent selected from the group comprising chloroform, dichloromethane and mixtures thereof, preferably acetonitrile or in combination thereof.
26. The process as claimed in claim 21, wherein process comprises optionally converting (R)-Ruxolitinib to its acid salt by reacting with an acid.
27. The process as claimed in claim 21, wherein the acid is selected from group comprising maleic acid, phosphoric acid, sulfuric acid, benzoic acid, citric acid, salicylic acid and mixtures thereof.