DESC:FIELD OF THE INVENTION
The present invention relates to a process of Ruxolitinib chiral resolution. The process of the present invention particularly relates to chiral resolution of rac-Ruxolitinib base to Ruxolitinib phosphate via chirally pure Ruxolitinib L-DPTA salt.

BACKGROUND OF THE INVENTION
Ruxolitinib chemically known as (R)-3-cyclopentyl-3-(4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl)propanenitrile of Formula I is a selective JAK1/JAK2 tyrosine kinase inhibitor,
Formula I
for the treatment of myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis.
US Patent No.7598257 discloses a process for the preparation of Ruxolitinib, wherein 3-cyclopentyl-3-[4-(7-[2-(trimethylsilyl)ethoxymethyl]-7H-pyrrolo[2,3-£/]-pyrimidin-4-yl)-lH-pyrazol-l-yl] propanenitrile of Formula Ila,

which on HPLC separation technique results in an enantiomer, (3R)-3-cyclopentyl-3-[4-(7-[2-(trimethylsilyl) ethoxy methyl]-7H-pyrrolo[2,3-£/]-pyrimidin-4-yl)-lH-pyrazol-l-yl] propanenitrile, which is then deprotected to give Ruxolitinib.
US Patent No. 8410265 describes a process for the preparation of (3R)-3-cyclopentyl-3-[4-(7-[2-(trimethylsilyl)ethoxymethyl]-7H-pyrrolo[2,3-£/]-pyrimidin-4-yl)-lH-pyrazol-l-yl] propane nitrile by resolution of the compound of Formula Ila with (+)-2,3-dibenzoyl-D-tartaric acid to predominantly obtain (2S,3S)-2,3-bis(benzoyloxy)succinic acid-(3R)-3-cyclopentyl-3-[4-(7-{[2- (trimethylsilyl)ethoxy]methyl}-7H-pyrrolo [2,3 -d\ -pyrimidin-4-yl)- lH-pyrazol- 1-yl]propanenitrile (1:1) and its subsequent treatment with a base. It further provides a process for the preparation of Ruxolitinib phosphate from (3R)-3-cyclopentyl-3-[4-(7-[2-(trimethylsilyl)ethoxymethyl]-7H-pyrrolo [2,3-d\ -pyrimidin-4-yl)- lH-pyrazol- 1-yl] propanenitrile. It further discloses a method of purifying (3R)-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propionitrile phosphate salt comprising recrystallizing (3R)-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl] propionitrile phosphate salt from a solvent mixture comprising methanol, 2-propanol, and n-heptane. US’265 have failed to disclose the chiral purity of Ruxolitinib phosphate.
There remains a need in the art to provide a process for preparation of Ruxolitinib phosphate salt having high chiral purity via chirally pure Ruxolitinib L-DPTA salt. This remains the objective of the present invention.

SUMMARY OF THE INVENTION
In accordance with the above, the present invention provides a process for preparation of Ruxolitinib phosphate salt with chiral purity =99.9% comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with L-(-)-Di-p-toluoyl tartaric acid or D-(+)-Di-p-toluoyl tartaric acid to obtain crude Ruxolitinib L-DPTA salt and Ruxolitinib D-DPTA salt respectively;
ii. Purifying the crude Ruxolitinib L-DPTA salt until the desired isomer of =99.9 chirality is obtained;
iii. Separating the undesired Ruxolitinib D-DPTA salt from the filtrate/MLR, isolating free base from filtrate/ MLR, converting Ruxolitinib base to its Ruxolitinib L-DPTA salt and purifying the crude Ruxolitinib L-DPTA salt until the desired isomer of =99.9 chirality is obtained;
iv. Combining the filtrates obtained in step (iii), optionally distilling or precipitating out the undesired Ruxolitinib D-DPTA salt and basifying Ruxolitinib L-DPTA salt to its base;
v. Converting Ruxolitinib base to its Ruxolitinib L-DPTA salt and purifying Ruxolitinib L-DPTA salt from the solvent or its mixtures thereof until the desired isomer of =99.9 chirality is obtained;
vi. Converting the Ruxolitinib L-DPTA salt obtained in step (iv) to its base followed by conversion to its Ruxolitinib phosphate with high chiral puirty.

In another aspect, the present invention provides a process for preparation of Ruxolitinib phosphate salt with chiral purity =99.9% from pure Ruxolitinib L-DPTA salt comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with L-(-)-Di-p-toluoyl tartaric acid to obtain crude solid Ruxolitinib L-DPTA salt and storing the filtrates;
ii. Purifying the solid crude Ruxolitinib L-DPTA salt of step (i) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA salt to the desired isomer of =99.9 chirality and storing the filtrates;
iii. Converting the pure Ruxolitinib L-DPTA salt to its base and further isolating Ruxolitinib phosphate as the first crop;
iv. Combining the filtrates MLR-4, MLR-5 and MLR-6 of step (i) and step (ii) and distilling under vacuum to obtain the residue, basified followed by addition of D-(+)-Di-p-toluoyl tartaric acid to precipitate out the undesired D-DPTA salt from the filtrate (MLR-7);
v. Concentrating the filtrate of step (iv) under vacuum to obtain the residue, basified followed by addition of L-(-)-Di-p-toluoyl tartaric acid to said base dissolved in the solvent and isolating the Ruxolitinib L-DPTA salt;
vi. Purifying the Ruxolitinib L-DPTA salt of step (v) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA salt (A) from the filtrates MLR-5, MLR-6, MLR-7 to the desired isomer of =99.9 chirality;
vii. Combining the filtrates MLR-8, MLR-9 of step (vi) and concentrating under vacuum to obtain the residue, basified followed by addition of L-(-)-Di-p-toluoyl tartaric acid to base dissolved in the solvent and isolating the Ruxolitinib L-DPTA salt (B) from the filtrate;
viii. Purifying Ruxolitinib L-DPTA salt (B) of step (vii) from the solvent repeatedly until the desired isomer =99.9 chirality is obtained;
ix. Combining Ruxolitinib L-DPTA salt (A) of step (vi) and Ruxolitinib L-DPTA salt (B) of step (viii) and converting to the base followed by conversion and isolation to Ruxolitinib phosphate.
In another aspect, the present invention provides a process for preparation of Ruxolitinib phosphate salt with chiral purity =99.9% from Ruxolitinib D-DPTA salt comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with D-(+)-Di-p-toluoyl tartaric acid to obtain crude Ruxolitinib D-DPTA salt, filtering, washing and concentrating the filtrate MLR-1 containing predominantly Ruxolitinib desired isomer;
ii. Isolating the base from the MLR-1 and preparing L-(-)-Di-p-toluoyl tartaric acid salt and isolating crude Ruxolitinib L-DPTA salt;
iii. Purifying the crude Ruxolitinib L-DPTA salt obtained in step (ii) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA salt and separating the filtrates;
iv. Converting the solid Ruxolitinib L-DPTA salt obtained in step (iii) to its base followed by conversion to Ruxolitinib phosphate as first crop;
v. Isolating free base from the filtrates of step (iii) and adding L-(-)-Di-p-toluoyl tartaric acid to the solution and isolating crude Ruxolitinib L-DPTA salt
vi. Purifying the crude Ruxolitinib L-DPTA salt obtained in step (v) from the solvent repeatedly and isolating pure Ruxolitinib L-DPTA salt with the desired isomer of =99.9 chirality and converting the pure Ruxolitinib L-DPTA salt of step (v) to its base followed by conversion to Ruxolitinib phosphate.

In an aspect, racemic Ruxolitinib used in the present invention is prepared by the process known in the art.

DETAILED DESCRIPTION OF THE INVENTION
The features of the present invention is described below in the various preferred and optional embodiments, however, should not be construed as limiting the scope of the invention.

The present invention relates to an efficient process for the preparation of Ruxolitinib phosphate salt with chiral purity =99.9% via conversion of racemic Ruxolitinib (Rac- Ruxolitinib) base to its Ruxolitinib L-DPTA salt or Ruxolitinib D-DPTA salt. The process for preparation of Ruxolitinib phosphate salt with high chiral purity is preferably carried out via the desired isomer Ruxolitinib L-DPTA salt.

In an embodiment, the undesired Ruxolitinib D-DPTA salt is removed from the filtrates obtained during the process and said filtrates containing the desired Ruxolitinib L-DPTA salt is converted to its base and further to the phosphate salt.

In another embodiment of the present process, Ruxolitinib phosphate salt with high chiral purity is prepared by conversion of racemic Ruxolitinib (Rac- Ruxolitinib) base to Ruxolitinib D-DPTA salt and isolating from the filtrates the desired isomer Ruxolitinib L-DPTA salt and converting to its base followed by conversion to its phosphate salt of high chiral purity.

The process of the present invention is efficient; the filtrates are preserved and used for isolation of desired and undesired isomer such that it leads to isolation of the intermediate Ruxolitinib L-DPTA salt and Ruxolitinib phosphate with chiral purity of =99.9%.

In an embodiment, the present invention discloses a process for preparation of Ruxolitinib phosphate salt with high chiral purity comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with L-(-)-Di-p-toluoyl tartaric acid or D-(+)-Di-p-toluoyl tartaric acid to obtain crude Ruxolitinib L-DPTA salt and Ruxolitinib D-DPTA salt respectively;
ii. Purifying the crude Ruxolitinib L-DPTA salt until the desired isomer of =99.9 chirality is obtained;
iii. Separating the undesired Ruxolitinib D-DPTA salt from the filtrate/MLR, isolating free base from filtrate/ MLR, converting Ruxolitinib base to its Ruxolitinib L-DPTA salt and purifying the crude Ruxolitinib L-DPTA salt until the desired isomer of =99.9 chirality is obtained;
iv. Combining the filtrates obtained in step (iii), optionally distilling or precipitating out the undesired Ruxolitinib D-DPTA salt and basifying Ruxolitinib L-DPTA salt to its base;
v. Converting Ruxolitinib base to its Ruxolitinib L-DPTA salt and purifying Ruxolitinib L-DPTA salt from the solvent or its mixtures thereof until the desired isomer of =99.9 chirality is obtained;
vi. Converting the Ruxolitinib L-DPTA salt obtained in step (iv) to its base followed by conversion to its Ruxolitinib phosphate with high chiral puirty.

In a preferred embodiment, the present invention relates to a process for preparation of Ruxolitinib phosphate salt with high chiral purity from pure Ruxolitinib L-DPTA salt comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with L-(-)-Di-p-toluoyl tartaric acid to obtain crude Ruxolitinib L-DPTA solid and separating the filtrates;
ii. Purifying the solid crude Ruxolitinib L-DPTA salt of step (i) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA salt to the desired isomer of =99.9 chirality and separating the filtrates;
iii. Converting the pure Ruxolitinib L-DPTA salt to its base and further isolating Ruxolitinib phosphate as the first crop;
iv. Combining the filtrates MLR-4, MLR-5 and MLR-6 of step (i) and step (ii) and distilling under vacuum to obtain the residue, basified followed by addition of D-(+)-Di-p-toluoyl tartaric acid to precipitate out the undesired D-DPTA salt from the filtrate (MLR-7);
v. Concentrating the filtrate of step (iv) under vacuum to obtain the residue, basified followed by addition of L-(-)-Di-p-toluoyl tartaric acid to said base dissolved in the solvent and isolating the Ruxolitinib L-DPTA salt;
vi. Purifying the L-DPTA salt of step (v) form the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA salt (A) from the filtrates MLR-5, MLR-6, MLR-7 to the desired isomer of =99.9 chirality;
vii. Combining the filtrates MLR-8, MLR-9 of step (vi) and concentrating under vacuum to obtain the residue, basified followed by addition of L-(-)-Di-p-toluoyl tartaric acid to base dissolved in the solvent and isolating the Ruxolitinib L-DPTA salt (B) from the filtrate;
viii. Purifying Ruxolitinib L-DPTA salt (B) of step (vii) from the solvent repeatedly until the desired isomer =99.9 chirality is obtained;
ix. Combining Ruxolitinib L-DPTA salt (A) of step (vi) and Ruxolitinib L-DPTA salt (B) of step (vii) and converting to the base followed by conversion and isolation of Ruxolitinib phosphate as second crop.

In another embodiment, the present invention relates to a process for preparation of Ruxolitinib phosphate salt with high chiral purity from Ruxolitinib D-DPTA salt comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with D-(+)-Di-p-toluoyl tartaric acid to obtain crude Ruxolitinib D-DPTA salt, filtering, washing and concentrating the filtrate MLR-1 containing predominantly Ruxolitinib desired isomer;
ii. Isolating free base from the MLR-1 and adding L-(-)-Di-p-toluoyl tartaric acid to the solution and isolating crude Ruxolitinib L-DPTA salt;
iii. Purifying the crude Ruxolitinib L-DPTA salt obtained in step (ii) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA and separating the filtrates;
iv. Converting the solid Ruxolitinib L-DPTA salt obtained in step (iii) to its base followed by conversion to Ruxolitinib phosphate as first crop;
v. Isolating free base from the filtrates of step (iii) and adding L-(-)-Di-p-toluoyl tartaric acid to the solution and isolating crude Ruxolitinib L-DPTA salt
vi. Purifying the crude Ruxolitinib L-DPTA salt obtained in step (v) from the solvent repeatedly and isolating pure Ruxolitinib L-DPTA salt with the desired isomer of =99.9 chirality; and
vii. Converting the pure Ruxolitinib L-DPTA salt of step (vi) to its base followed by conversion to Ruxolitinib phosphate.
In an embodiment, racemic Ruxolitinib used in the present invention is prepared by the process known in the art.

The solvent used in the process of the present invention is selected from the group consisting of lower alcohols, nitriles, esters, hydrocarbons, ketones, halogenated hydrocarbons and the like alone or mixtures thereof.

The conversion of the salt to the base in the present process is carried out in presence of alkali or alkaline earth metal carbonates or bicarbonates.

In the process of the present invention, Ruxolitinib base is converted to its phosphate using known phosphorylating agents, preferably phosphoric acid.

The temperature employed in the processes of the present invention ranges between 45oC to 110oC; preferably between 50oC to 85oC.

The L-(-)-Di-p-toluoyl tartaric acid or D-(+)-Di-p-toluoyl tartaric acid is used in the present invention in an amount ranging between 0.3-0.6equiv.

The reaction of racemic Ruxolitinib (Rac- Ruxolitinib) base with D-(+)-Di-p-toluoyl tartaric acid or L-(-)-Di-p-toluoyl tartaric acid is carried out at a temperature in the range of 50oC to 60oC.

The purification of crude Ruxolitinib L-DPTA salt is carried out in the solvent selected from lower alcohols, nitriles alone or mixtures thereof; preferably the solvent is acetonitrile, methanol alone or mixtures thereof at a temperature in the range of 60oC to 70oC. The purification is carried out multiple times until the content of the undesired isomer i.e. D-DPTA salt as checked by chiral HPLC is NMT 0.10-0.13%.

The filtrates obtained in the process of the present invention as MLRs are preserved for subsequent isolation of the crude product(s) of desired isomer.

In an aspect, the intermediate Ruxolitinib L-DPTA salt and Ruxolitinib phosphate has the chiral purity of =99.9%.

Examples:
Example 1: (A) Process for Ruxolitinib Phosphate 1st crop

(i) Ruxolitinib L-DPTA salt preparation
In clean and dry RBF, acetonitrile (15vol) and Rac-Ruxolitinib base was charged. Temperature of the reaction mass was raised to 55±5°C. L-(-)-Di-p-toluoyl tartaric acid (0.5 equiv) was charged and the reaction mass was maintained for 30 minutes. The obtained solution was cooled to room temperature and stirred for 1hr. Temperature of the obtained slurry mass was heated to 72±3°C and maintained for 30 minutes. It was then gradually cooled to room temperature and maintained for 2 hrs. The crude L-DPTA salt was collected by filtration, washed with acetonitrile, and dried under vacuum (Note: MLR-4 was preserved for the 2nd crop isolation).

(ii) Purification 1 of crude Ruxolitinib L-DPTA salt
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt of step (i) was charged. The temperature was raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product was collected by filtration, washed with acetonitrile, and dried under vacuum. (Note: MLR-5 was preserved for the 2nd crop isolation)

(iii) Purification 2 of crude Ruxolitinib L-DPTA salt
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt of step no. (ii) was charged. The temperature was raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product was collected by filtration, washed with acetonitrile, and dried under vacuum. (Note: MLR-6 was preserved for the 2nd crop isolation)
The dried sample was checked for the content of undesired isomer by chiral HPLC (limit NMT 0.13%)
Note: If the content of undesired isomer is more, same purification process is performed.

(iv) Preparation of Ruxolitinib Phosphate
In clean and dry RBF, Ruxolitinib L-DPTA salt, Ethyl acetate (7 vol) and aqueous sodium carbonate solution (5 vol) was charged. The mixture was stirred till clear solution and then layers were separated. Aqueous layer was extracted with ethyl acetate (5 vol), the combined organic layer was washed with water. Organic layer was concentrated under vacuum to get the Ruxolitinib base which was taken in IPA (5.5 vol) and to the obtained solution phosphoric acid (1.35 equiv) solution in IPA was added at 52±3°C and maintained for 1 hr. The mixture was gradually cooled to room temperature; the product was collected by filtration, washed with IPA, dried under vacuum to get Ruxolitinib phosphate.
The process for Ruxolitinib Phosphate 1st crop is depicted in the flow chart below:
Activity Remark MLR

Ruxolitinib base Racemic Isomers 50:50

L-DPTA salt preparation Acetonitrile Desired isomer ratio = 85%
MLR-4

L-DPTA salt Purification in Acetonitrile + MeOH Desired isomer ratio = 99%
MLR-5

L-DPTA salt Purification in Acetonitrile + MeOH Desired isomer = 99.85
MLR-6

Base 1

Phosphate salt preparation

Ruxolitinib phosphate (Crop 1)

(B)- Process for preparation Ruxolitinib Phosphate 2nd crop
(v) Removal of Undesired isomer by D-DPTA salt preparation
MLR of crude (MLR-4), 1st purification (MLR-5) and 2nd purification (MLR-6) of Ruxolitinib L-DPTA salt were combined and distilled out under vacuum. To the obtained residue Ethyl acetate (7 vol) and aqueous sodium carbonate solution (5 vol) was charged and stirred till clear solution. Layers were separated, aqueous layer was extracted with ethyl acetate (5 vol) and combined organic layers was washed with water (5 vol). The organic layer was concentrated under vacuum and to the obtained residue acetonitrile (10 vol) was added. The temperature of the mass was raised to 55±5°C and to the obtained solution D-(+)-Di-p-toluoyl tartaric acid (0.5 equiv) was charged. The reaction mass maintained at 55±5°C for 30 min and then it was gradually cooled to room temperature for 1hr. The temperature of the mixture was again raised to 72±3°C for 30 minutes. Then, it was gradually cooled to room temperature and maintained for 2 hrs. Precipitated D-DPTA salt was collected by filtration, washed with acetonitrile (Note: MLR-7 was preserved and used for the 2nd crop isolation).

(vi) Preparation of L-DPTA salt of 2nd crop - I
MLR of D-DPTA salt was concentrated out under vacuum and to the obtained residue ethyl acetate (7 vol), aqueous sodium carbonate solution (5 vol) was charged. The mixture was stirred till clear solution, layers were separated. Aqueous layer was extracted with ethyl acetate (5 vol), combined organic layer washed with water (5 vol). Organic layer was concentrated under vacuum and to the obtained residue acetonitrile (4 vol) was charged. Temperature of the obtained solution was raised to 55±5°C and then L-(-)-Di-p-toluoyl tartaric acid (0.2 equiv) was charged. The reaction mass was maintained at 55±5°C for 30 min and then it was gradually cooled to room temperature for 1 hr. The temperature of the mixture was again raised to 72±3°C for 30 minutes and then, it was gradually cooled to room temperature for 2 hrs. The L-DPTA salt was collected by filtration, washed with acetonitrile, dried under vacuum.
(vii) Purification 1 of L-DPTA salt of 2nd crop - I
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt was charged. The temperature was raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product was collected by filtration, washed with acetonitrile, and dried under vacuum. (Note: MLR-8 was preserved for the 2nd crop isolation)

(viii) Purification 2 of L-DPTA salt of 2nd crop - I
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt was charged. The temperature was raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product was collected by filtration, washed with acetonitrile, and dried under vacuum. (Note: MLR-9 was preserved for the 2nd crop isolation)
The dried sample was checked for the content of undesired isomer by chiral HPLC (limit NMT 0.13%)
Note: If the content of undesired isomer is more, same purification process is performed.

(ix) Preparation of L-DPTA salt of 2nd crop - II
MLR of 1st and 2nd purification of L-DPTA salt (MLR-8 and MLR-9 ) of 2nd crop - I were combined and concentrated out under vacuum. To the obtained residue, ethyl acetate (3 vol), aqueous sodium carbonate solution (2 vol) was charged. The mixture was stirred till clear solution, layers were separated. Aqueous layer was extracted with ethyl acetate (2 vol), combined organic layer washed with water (2 vol) and concentrated under vacuum. To the obtained residue acetonitrile (1.5 vol) was charged and then temperature was raised to 55±5°C. L-(-)-Di-p-toluoyl tartaric acid (0.05 equiv) was charged. The reaction mass maintained at 55±5°C for 30 min and then it was gradually cooled to room temperature for 1 hr. The temperature of the mixture was again raised to 72±3°C for 30 minutes. Then, it was gradually cooled to room temperature and maintained for 2 hrs. The L-DPTA salt was collected by filtration, washed with acetonitrile, dried under vacuum.
(x) Purification 1 of L-DPTA salt of 2nd crop – II
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt was charged. The temperature was raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product was collected by filtration, washed with acetonitrile, and dried under vacuum.
(xi) Purification 2 of L-DPTA salt of 2nd crop – II
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt was charged. The temperature was raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product was collected by filtration, washed with acetonitrile, and dried under vacuum.
The dried sample was checked for the content of undesired isomer by chiral HPLC (limit NMT 0.13%)
Note: If the content of undesired isomer is more, same purification process is performed.

(xii) Preparation of Ruxolitinib Phosphate salt (Crop-2):
Ruxolitinib L-DPTA salt of 2nd crop – I and II were charged in Ethyl acetate (7 vol) and aqueous sodium carbonate solution (5 vol). The mixture was stirred till clear solution and then layers were separated. Aqueous layer was extracted with ethyl acetate (5 vol), combined organic layer was washed with water. Organic layer was concentrated under vacuum to get the Ruxolitinib base which was taken in IPA (5.5 vol) and then phosphoric acid (1.35 equiv) solution in IPA was added at 52±3°C and maintained for 1 hr. The mixture was gradually cooled to room temperature the product was collected by filtration, washed with IPA, dried under vacuum to get Ruxolitinib phosphate 2nd crop.
Total Yield: 83.33% (Desired isomer of Ruxolitinib Base after resolution including 2nd crop)
Total Yield: 68.00% (Ruxolitinib Phosphate API)
Chiral HPLC purity: 99.96% (Desired isomer)
The process for Ruxolitinib phosphate 2nd crop is described in the flow chart below:
Activity Remark MLR
MLR-4 + MLR-5 + MLR-6

Distillation Undesired isomer
= 75%

Basification

D-DPTA salt preparation Acetonitrile Undesired isomer = 95
MLR-7
MLR-7 Desired isomer = 75

Basification

Ruxolitinib L-DPTA (A) salt preparation in Acetonitrile Desired isomer ratio = 90
MLR for disposal

Ruxolitinib L-DPTA (A) salt Purification in Acetonitrile + MeOH Desired isomer ratio = 99
MLR-8

Ruxolitinib L-DPTA salt (A) Purification in Acetonitrile + MeOH Desired isomer = 99.85
MLR-9

Base 2
MLR-8 + MLR-9

Basification

Ruxolitinib L-DPTA (B) salt preparation Acetonitrile Desired isomer ratio = 90

Ruxolitinib L-DPTA (B) salt Purification in Acetonitrile + MeOH Desired isomer ratio = 99

Ruxolitinib L-DPTA salt (B) Purification in Acetonitrile + MeOH Desired isomer = 99.85

Ruxolitinib L-DPTA salt (A) and (B)

Base 3 + Base 2

Phosphate salt preparation

Ruxolitinib phosphate crop 2

Example 2: Process for Ruxolitinib Phosphate 1st crop
(i) Ruxolitinib-DPTA salt preparation
In clean and dry RBF, acetonitrile (15 vol) and Rac-Ruxolitinib base is charged. Temperature of the reaction mass is raised to 55±5°C. D-(+)-Di-p-toluoyl tartaric acid (0.5 equiv) is charged and the reaction mass is maintained for 30 minutes. The obtained clear solution is cooled to room temperature and stirred for 1 hr. It is then gradually cooled to room temperature and maintained for 2 hrs. Reaction mass is filtered, solid is washed with acetonitrile. Filtrate MLR-1 containing predominantly Ruxolitinib desired isomer is collected and concentrated under vacuum. To the obtained residue ethyl acetate (7 vol), aqueous sodium carbonate solution (5 vol) is charged. The mixture is stirred till clear solution, layers are separated. Aqueous layer is extracted with ethyl acetate (5 vol), combined organic layer washed with water (5 vol). Organic layer is concentrated under vacuum. To the obtained residue acetonitrile (7.5 vol) is charged. Temperature of the obtained solution is raised to 55±5°C and then L-(-)-Di-p-toluoyl tartaric acid (0.45 equiv) is charged. The reaction mass is maintained at 55±5°C for 30 min and then it is gradually cooled to room temperature for 1 hr. The temperature of the mixture is again raised to 72±3°C for 30 minutes and then, it is gradually cooled to room temperature for 2 hrs. The crude Ruxolitinib L-DPTA salt is collected by filtration, washed with acetonitrile, dried under vacuum.
(ii) 1st Purification of Ruxolitinib L-DPTA salt
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt is charged. The temperature is raised to 70±3°C and then gradually cooled to room temperature for 2 hrs. The product is collected by filtration, washed with acetonitrile, and dried under vacuum. (Note: MLR-2 is preserved for the 2nd crop isolation).
(iii) 2nd Purification of Ruxolitinib L-DPTA salt
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt is charged. The temperature is raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product is collected by filtration, washed with acetonitrile, and dried under vacuum. (Note: MLR-3 is preserved for the 2nd crop isolation)
The dried sample is checked for the content of undesired isomer by chiral HPLC (limit NMT 0.13%)
Note: If the content of undesired isomer is more, same purification process is performed.
(iv) Preparation of Ruxolitinib Phosphate
In clean and dry RBF, Ruxolitinib L-DPTA salt, Ethyl acetate (7 vol) and aqueous sodium carbonate solution (5 vol) is charged. The mixture is stirred till clear solution and then layers are separated. Aqueous layer is extracted with ethyl acetate (5 vol), the combined organic layer is washed with water. Organic layer is concentrated under vacuum to get the Ruxolitinib base which is taken in IPA (5.5 vol) and to the obtained solution phosphoric acid (1.35 equiv) solution in IPA is added at 52±3°C and maintained for 1 hr. The mixture is gradually cooled to room temperature, the product is collected by filtration, washed with IPA, dried under vacuum to get Ruxolitinib phosphate.
(v) Preparation of L-DPTA salt of from MLR of Purification of crude Ruxolitinib L-DPTA salt
MLR of 1st and 2nd purification (MLR- 2 and MLR- 3) of Ruxolitinib crude L-DPTA salt are combined and concentrated out under vacuum. To the obtained residue, ethyl acetate (3 vol), aqueous sodium carbonate solution (2 vol) is charged. The mixture is stirred till clear solution, layers are separated. Aqueous layer is extracted with ethyl acetate (2 vol), combined organic layer washed with water (2 vol) and concentrated under vacuum. To the obtained residue acetonitrile (1.5 vol) is charged and then temperature is raised to 55±5°C. L-(-)-Di-p-toluoyl tartaric acid (0.05 equiv) is charged. The reaction mass maintained at 55±5°C for 30 min and then it is gradually cooled to room temperature for 1 hr. The temperature of the mixture is again raised to 72±3°C for 30 minutes. Then, it is gradually cooled to room temperature and maintained for 2 hrs. The Ruxolitinib L-DPTA salt is collected by filtration, washed with acetonitrile, dried under vacuum.
(vi) Purification 1 of Ruxolitinib L-DPTA
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt is charged. The temperature is raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product is collected by filtration, washed with acetonitrile, and dried under vacuum.
(vii) Purification 2 of Ruxolitinib L-DPTA
In clean and dry RBF, acetonitrile (8.5 vol), methanol (1.5 vol) and Ruxolitinib L-DPTA salt is charged. The temperature is raised to 67±3°C and then gradually cooled to room temperature for 2 hrs. The product is collected by filtration, washed with acetonitrile, and dried under vacuum.
The dried sample is checked for the content of undesired isomer by chiral HPLC (limit NMT 0.13%)
Note: If the content of undesired isomer is more, same purification process is performed.
(viii) Preparation of Ruxolitinib Phosphate
In clean and dry RBF, Ruxolitinib L-DPTA salt of (step no VII vii), Ethyl acetate (7 vol) and aqueous sodium carbonate solution (5 vol) is charged. The mixture is stirred till clear solution and then layers are separated. Aqueous layer is extracted with ethyl acetate (5 vol), the combined organic layer is washed with water. Organic layer is concentrated under vacuum to get the Ruxolitinib base which is taken in IPA (5.5 vol) and to the obtained solution phosphoric acid (1.35 equiv) solution in IPA is added at 52±3°C and maintained for 1 hr. The mixture is gradually cooled to room temperature, the product is collected by filtration, washed with IPA, dried under vacuum to get Ruxolitinib phosphate.
The process of example 2 is depicted in the Flow Chart below:
1st crop:
Activity Remark MLR/Solid
Ruxolitinib base Racemic Isomers about 50:50

Ruxolitinib D-DPTA salt preparation in Acetonitrile Undesired isomer = 85
Solid

MLR 1 Desired isomer = 85

Basification

Ruxolitinib L-DPTA salt preparation in Acetonitrile Desired isomer ratio = 90
MLR for disposal
Solid

Ruxolitinib L-DPTA salt 1st Purification in Acetonitrile + MeOH Desired isomer ratio = 99
MLR 2
Solid

Ruxolitinib L-DPTA salt 2nd Purification in Acetonitrile + MeOH Desired isomer = 99.85
MLR 3
Solid

Base

Ruxolitinib phosphate
(1st crop)

2nd crop:
Activity Remark
MLR 2 + MLR 3

Basification

Ruxolitinib L-DPTA salt preparation Acetonitrile Desired isomer ratio = 90
Solid

Ruxolitinib L-DPTA salt 1st Purification in Acetonitrile + MeOH Desired isomer ratio = 99
Solid

Ruxolitinib L-DPTA salt 2nd Purification in Acetonitrile + MeOH Desired isomer = 99.85
Solid

Base

Ruxolitinib phosphate
(2nd crop)

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
,CLAIMS:1. A process for preparation of Ruxolitinib phosphate salt with chiral purity =99.9%.comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with L-(-)-Di-p-toluoyl tartaric acid or D-(+)-Di-p-toluoyl tartaric acid to obtain crude Ruxolitinib L-DPTA salt and Ruxolitinib D-DPTA salt respectively;
ii. Purifying the crude Ruxolitinib L-DPTA salt until the desired isomer of =99.9 chirality is obtained;
iii. Separating the undesired Ruxolitinib D-DPTA salt from the filtrate/MLR, isolating free base from filtrate/ MLR, converting Ruxolitinib base to its Ruxolitinib L-DPTA salt and purifying the crude Ruxolitinib L-DPTA salt until the desired isomer of =99.9 chirality is obtained;
iv. Combining the filtrates obtained in step (iii), optionally distilling or precipitating out the undesired Ruxolitinib D-DPTA salt and basifying Ruxolitinib L-DPTA salt to its base;
v. Converting Ruxolitinib base to its Ruxolitinib L-DPTA salt and purifying Ruxolitinib L-DPTA salt from the solvent or its mixtures thereof until the desired isomer of =99.9 chirality is obtained;
vi. Converting the Ruxolitinib L-DPTA salt obtained in step (iv) to its base followed by conversion to its Ruxolitinib phosphate with high chiral puirty.

2. The process as claimed in claim 1, wherein Ruxolitinib phosphate salt with chiral purity =99.9% is prepared from pure Ruxolitinib L-DPTA salt comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with L-(-)-Di-p-toluoyl tartaric acid and filtering out crude solid Ruxolitinib L-DPTA salt and separating the filtrates;
ii. Purifying the solid crude Ruxolitinib L-DPTA salt of step (i) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA salt to the desired isomer of =99.9 chirality and separating the filtrates;
iii. Converting the pure Ruxolitinib L-DPTA salt to its base and further isolating Ruxolitinib phosphate as the first crop;
iv. Combining the filtrates MLR-4, MLR-5 and MLR-6 of step (i) and step (ii) and distilling under vacuum to obtain the residue, basified followed by addition of D-(+)-Di-p-toluoyl tartaric acid to precipitate out the undesired D-DPTA salt from the filtrate (MLR-7);
v. Concentrating the filtrate of step (iv) under vacuum to obtain the residue, basified followed by addition of L-(-)-Di-p-toluoyl tartaric acid to said base dissolved in the solvent and isolating the Ruxolitinib L-DPTA salt;
vi. Purifying the Ruxolitinib L-DPTA salt of step (v) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA salt (A) from the filtrates MLR-5, MLR-6, MLR-7 to the desired isomer of =99.9 chirality;
vii. Combining the filtrates MLR-8, MLR-9 of step (vi) and concentrating under vacuum to obtain the residue, basified followed by addition of L-(-)-Di-p-toluoyl tartaric acid to base dissolved in the solvent and isolating the Ruxolitinib L-DPTA salt (B) from the filtrate;
viii. Purifying Ruxolitinib L-DPTA salt (B) of step (vii) from the solvent repeatedly until the desired isomer =99.9 chirality is obtained;
ix. Combining Ruxolitinib L-DPTA salt (A) of step (vi) and Ruxolitinib L-DPTA salt (B) of step (viii) and converting to the base followed by conversion and isolation to Ruxolitinib phosphate as second crop.
3. The process as claimed in claim 1, wherein Ruxolitinib phosphate salt with chiral purity =99.9%.is prepared from Ruxolitinib D-DPTA salt comprising;
i. Reacting racemic Ruxolitinib (Rac- Ruxolitinib) base with D-(+)-Di-p-toluoyl tartaric acid to obtain crude Ruxolitinib D-DPTA salt, filtering, washing and concentrating the filtrate MLR-1 containing predominantly Ruxolitinib desired isomer;
ii. Isolating free base from the MLR-1 and adding L-(-)-Di-p-toluoyl tartaric acid to the solution and isolating crude Ruxolitinib L-DPTA salt;
iii. Purifying the crude Ruxolitinib L-DPTA salt obtained in step (ii) from the solvent repeatedly and isolating the purified solid Ruxolitinib L-DPTA and separating the filtrates;
iv. Converting the solid Ruxolitinib L-DPTA salt obtained in step (iii) to its base followed by conversion to Ruxolitinib phosphate as first crop;
v. Isolating free base from the filtrates of step (iii) and adding L-(-)-Di-p-toluoyl tartaric acid to the solution and isolating crude Ruxolitinib L-DPTA salt;
vi. Purifying the crude Ruxolitinib L-DPTA salt obtained in step (v) from the solvent repeatedly and isolating pure Ruxolitinib L-DPTA salt with the desired isomer of =99.9 chirality; and
vii. Converting the pure Ruxolitinib L-DPTA salt of step (vi) to its base followed by conversion to Ruxolitinib phosphate.
4. The process as claimed claim 1, wherein racemic Ruxolitinib is prepared by a known process.

5. The process as claimed in any one of the claims 1 to 3, wherein the Ruxolitinib base is converted to its phosphate with phosphorylating agent.

6. The process as claimed in claim 5, wherein the phosphorylating agent is phosphoric acid.

7. The process as claimed in any one of the claims 1 to 3, wherein the L-(-)-Di-p-toluoyl tartaric acid or D-(+)-Di-p-toluoyl tartaric acid is in an amount ranging between 0.3-0.6equiv.

8. The process as claimed in any one of the claims 1 to 3, wherein the solvent is selected from the group consisting of lower alcohols, nitriles, esters, hydrocarbons, ketones, halogenated hydrocarbons and the like alone or mixtures thereof.

9. The process as claimed in claim 8, wherein the solvent is selected from methanol, IPA, ethyl acetate, acetonitrile, water alone or mixtures thereof.

10. The process as claimed in any one of the claims 1 to 3, wherein the temperature of the process ranges between 45oC to 110oC; preferably between 50oC to 85oC.

11. The process as claimed in any one of the claims 1 to 3, wherein the step of conversion of salt to its base is carried out in presence of alkali or alkaline earth metal carbonates or bicarbonates.

12. The process as claimed in any one of the claims 1 to 3, wherein the step of reaction of racemic Ruxolitinib to L-(-)-Di-p-toluoyl tartaric acid or D-(+)-Di-p-toluoyl tartaric acid is carried out at a temperature in the range of 50oC to 60oC.

13. The process as claimed in any one of the claims 1 to 3, wherein the step of purification of crude Ruxolitinib L-DPTA salt is carried out in presence of solvents selected from lower alcohols, nitriles alone or mixtures thereof.

14. The process as claimed in claim 13, wherein the solvent is acetonitrile, methanol alone or mixtures thereof.

15. The process as claimed in any one of the claims 1 to 3, wherein the step of purification of crude Ruxolitinib L-DPTA salt is carried out at a temperature of 60oC to 70oC.