DESC:
FIELD OF INVENTION
The present disclosure is in relation to synthetic organic chemistry. The invention is in relation to a method of preparation of Glycolipid carboxylic acids and its salts. More particularly, the invention relates to preparation of compounds of Formula I and its salts via compounds of Formula 1-d and Formula II. The method provides an economical and environmentally benign approach to prepare complex organic compounds.
BACKGROUND OF INVENTION
Glycolipids are essential constituents of cellular membranes consisting of a sugar and lipid moiety. It is ubiquitously known that Glycolipids are important for cell aggregation, dissociation and also in specific cellular contact and for signal transduction. It also acts as a promising delivery system in RNA interference (RNAi) therapeutics. This application is broadly used as a potential therapeutic to reversibly silence any gene and has gained impetus in research. To achieve the clinical potential of RNAi, delivery materials are required to transport short interfering RNA (siRNA) to the site of action in the cells of target tissues.
Glycolipids such as N-Acetylgalactosamine (GalNAc) derivatives are important compounds for delivery of drugs. Its conjugates have been developed by directly conjugating delivery material to the siRNA cargo. The approach leads to well-defined, single-component system that uses only equimolar amounts of delivery material and siRNA. Therapeutics demand compounds in pristine form to minimize undesirable side effects and dosage. However, getting a pristine compound is a challenge, specifically with the said complex molecules.
N-Acetylgalactosamine (GalNAc) derivatives are sensitive Glycolipids due to large structure and easily susceptible functional groups.
The prior art methods (WO2014025805) to prepare the said compounds involves harsh reaction conditions, multiple steps, low yields of the target compounds with low chemical purity. The methods of preparation are difficult for its large scale preparation, economically. Further, considering the significance of the compounds it is necessary to develop robust, an economical and environmentally benign approach to prepare the said complex glycolipids and its potential intermediates with very high purity. The present inventors have surprisingly developed an efficient process which ameliorates the aforesaid shortcomings of the prior art.
OBJECTS OF INVENTION
It is an object of the present invention to provide a process for the preparation of compounds of Formula I and its salts via intermediate compounds of Formula 1-d and Formula II.
It is another object of the present invention to provide a process for the preparation of compounds of Formula I which involve mild reaction conditions, few steps, high yields of the target compounds with high chemical purity.
It is another object of the present invention to provide a process for the preparation of compounds of Formula I which can be prepared on a large scale is robust, economical and environmentally benign.
It is yet another object of the present invention to provide a process for the preparation of intermediate compounds of Formula 1-d and Formula II.
SUMMARY OF INVENTION
According to an aspect of the present invention there is provided a compound of Formula 1-d
1-d
Wherein R1 is selected from allyl, alkyl, aryl or arylalkyl groups
Wherein the said group may be linear, branched, cyclic with or without being substituted with functional groups- selected from but not limited to halogens, nitro, amine, aldehyde, carbonyl, hydroxyl.
Wherein the said alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, tert-butyl;
aryl groups are phenyl, naphthyl groups;
aralkyl or substituted aralkyl are Benzyl, p-Methoxy benzyl.
“n” range from 0 to 15.
According to another aspect of the present invention there is provided a process for preparing compounds of Formula 1-d comprising the steps of:
a. Reacting compound of Formula 1-a with mono succinyl esters to obtain compound of Formula 1-b;

b. Deprotecting the Fluorenylmethyloxycarbonyl (Fmoc) group from Formula 1-b to obtain compound of Formula 1-c;

c. Coupling compound of Formula 1-c with dioic acids to obtain a compound of Formula 1-d.

According to another aspect of the present invention, there is provided a process of preparing compounds of Formula II, comprising the steps of:
a. reacting compounds of Formula 1-d with compound of Formula 1-e

in the presence of coupling reagent, to obtain compounds of Formula II.

Formula II
Wherein R1 is selected from allyl, alkyl, aryl or arylalkyl groups
Wherein R2 is selected from alkyl, aryl, alkoxy, aryloxy or arylalkyl groups
Wherein the said group may be linear, branched, cyclic with or without being substituted with functional groups- selected from but not limited to halogens, nitro, amine, aldehyde, carbonyl, hydroxyl.
Wherein the said alkyl groups are methyl, ethyl, propyl, isopropyl butyl, tert-butyl;
aryl groups are phenyl, naphthyl groups;
aralkyl or substituted aralkyl are Benzyl, p-Methoxy benzyl.
“l’ and “m” range from 0 to 5; and “n” range from 0 to 15.
According to yet another aspect of the present invention, there is provided a process of preparing compounds of Formula I and salts thereof comprising the steps of:
a. performing selective ester hydrolysis of compounds of Formula II using lipase to obtain compounds of Formula I and its salts.
or
b. conducting a palladium catalysed conversion of esters of Formula II to corresponding carboxylic acids of Formula I and its salts.

Formula I
Wherein R2 is selected from alkyl, aryl, alkoxy, aryloxy or arylalkyl groups
Wherein the said group may be linear, branched, cyclic with or without being substituted with functional groups- selected from but not limited to halogens, nitro, amine, aldehyde, carbonyl, hydroxyl.
Wherein the said alkyl groups are methyl, ethyl, propyl, isopropyl butyl, tert-butyl;
aryl groups are phenyl, naphthyl groups;
aralkyl or substituted aralkyl are Benzyl, p-Methoxy benzyl.
“l’ and “m” range from 0 to 5; and “n” range from 0 to 15.
In one embodiment, triethylamine salt is made by using triethylamine.
The compound, process and the method of making novel intermediary compound and compounds of Formula I and its salts disclosed herein may be implemented in any means for achieving various aspects, and may be executed to produce compounds of Formula I and its salts in a large scale.
DESCRIPTION OF INVENTION
The following description is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the scope of the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, steps or components but does not preclude the presence or addition of one or more other features, steps, components or groups thereof.

The present invention relates to a method for preparing glycolipid carboxylic acids and their salts. The present invention outlines a process for synthesizing compounds of Formula I and their salts via intermediates of Formula 1-d and Formula II. This method offers a cost-effective and environmentally friendly approach for the preparation of complex organic molecules.
In an embodiment, general method of preparation of the compound of Formula I is given in Scheme–A. Accordingly, the method involves simple steps of preparation of compound of Formula 1-d which is further developed to compound of Formula I and its salt, wherein the first step is coupling compound of Formula (1-a) with mono succinic esters to obtain compound of Formula (1-b),deprotection of Fmoc group of compounds of Formula (1-b) with piperidine to obtain compound of Formula (1-c), coupling compounds of Formula (1-c) with dicarboxylic acid to obtain compound of Formula (1-d), coupling compounds of Formula (1-d) with amine of Formula (1-e) to obtain compound of Formula II and Selective hydrolysis of ester of Formula II using lipase to obtain compounds of Formula I. The compounds of Formula I are further converted to its salts.

Scheme- A
Wherein R1 is selected from allyl, alkyl, aryl or arylalkyl groups;
R2 is selected from alkyl, aryl, or arylalkyl groups
Wherein the said group may be linear, branched, cyclic with or without being substituted with functional groups- selected from but not limited to halogens, nitro, amine, aldehyde, carbonyl, hydroxyl;
wherein the said alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, tert-butyl;
aryl groups are phenyl, naphthyl groups;
aralkyl or substituted aralkyl are Benzyl, p-Methoxy benzyl, trityl;
“l’ and “m” range from 0 to 5; and “n” range from 0 to 15.
In an embodiment of the present invention, Lipase (crude, purified, immobilized) selected from the list given in Table 1 is adopted for the hydrolysis.
In still another embodiment, the lipase load for the reaction can vary between 1-100% wt/wt as compared to reactant.
The enzymes are procured from commercial sources or produced in-house using recombinant DNA technology. Microorganisms are not developed in house but procured from commercial source. The genetic resources are based on literature information, were chemically synthesized and cloned into appropriate vectors.
Table 1: List of Lipases adoptable for selective hydrolysis
Sr.No Lipase name Source (Micro-organism)
1 Lipase CL “Amano’’ Aspergillus oryzae
2 Lipase from porcine pancreas Porcine pancreas lipase (PPL)
3 Lipase AY “Amano”30SD Candida cylindracea
4 Lipase R “Amano” Penicilliumroqueforti
5 Lipase A “Amano”12 Aspergillus niger
6 Lipase MER “Amano” Rhizopusoryzae
7 Lipase DF “Amano”15 Rhizopusoryzae
8 Newlase F Rhizopusniveus
9 Lipase MH “Amano”10SD Mucorjavanicus
10 Lipase G “Amano”50
Mono, Di-glyceride Lipase Penicilliumcamembertii
11 Lipase PS “Amano” Burkholderiacepacia
12 Lipase AK “Amano” Burkholderiacepacia
13 Lipase PS ‘’Amano” IME
14 Novozym 435 (CALB lipase) Candida antarctica B
15 LipozymeTL IM Thermomyceslanuginosus
16 Novozym 40086 Rhizomucormehei
17 Lipozyme TL 100L Thermomyceslanuginosus
18 Novocor AD L (CALA) Candida antarctica A
19 Resinase HT Aspergillus oryzae
20 Palatase 20000 L Rhizomucormiehei
21 Novozym 51032 Aspergillus microorganism
22 Subtilisin A Bacillus subtilis
23 Alcalase
24 Savinase
25 Esperase
26 Neutrase Bacillus amyloliquefaciens
27 rTrypsin
28 SPRIN imibond THERMOLYSIN Geobacillus sp.
29 SPRIN epobond THERMOLYSIN Geobacillus sp.
30 Protease from Bacillus Licheniformis Bacillus licheniformis
31 Novozym 388 Rhizomucormiehei
32 Lipex 100L Aspergillus oryzae
33 Acylase "Amano" Aspergillus melleus
34 Esperase 8.0 L Bacillus lentus
35 Lipase AK "Amano" 20
36 Protease N "Amano" Bacillus subtilis
37 Protease S "Amano" Bacillus sp.
38 Lipase AS "Amano" Aspergillus niger
39 Lipase PS "Amano" SD Bulkholderiacepacia
40 Neutrase 0.8 L Bacillus amyloliquefaciens
41 Savinase 16L, Type EX Bacillus lentus
42 ASSEMBLASE liquid Escherichia coli
43 Lipase AY "Amano" 30SD-K Candida rugosa
44 Lipase MH "Amano" 10SD Mucorjavanicus
45 Lipase A "Amano" 12-K Aspergillus niger
46 Lipase DF "Amano" 15-K Rhizopusoryzae
47 Papain from papaya latex, P3375-25G Carica papaya
48 Alcalase Bacillus licheniformis
49 Trypsin from bovine pancreas cat: 93610 Bostaurus
50 Lipase PS ‘’Amano” IME
51 Lipase IME ( 90 )
52 Lipase IME ( 95 )
53 Klietase ( amylase)
54 Amano enzyme CES NL-1
55 Amano enzyme CES NL-2
56 Amano enzyme CES L-1
57 Amano enzyme CES L-2
58 Amano enzyme CES L-3
59 Amano enzyme CES L-4
60 Amano enzyme CES L-5
61 Amano enzyme CES L-6
62 Amano enzyme CES L-7
63 AddzymeCalB Candida antartica lipase B
64 Addzyme TL Thermomyceslanuginosus
65 Addzyme RD Rhizopusdelemar
67 Lipase MY Candida rugosa
68 Lipase ALC Achromobacter sp.
69 Lypolyve AN Aspergillus niger
70 Lypolyve CC Candida cylindracea
71 Lipomod 34P-L034P Candida cylindracea
72 Lipomod 627P-L627P Rhizopusoryzae
73 Lipase F-DS Rhizopusoryzae
74 Novolime (Novozymes)
75 GreasexNovoCor AD (Novozymes)
76 Lipopan F (Novozymes)
77 Resinase Candida rugosa
78 Noopazyme (Novozymes)
79 CalB Lipase – Anthem Candida antartica
80 Lipase – Anthem Thermomyceslanuginosus
81 Lipase – Anthem Serratiamarcescens
82 Lipase – Anthem Bacillus megaterium

In another embodiment the reaction parameters like coupling agent, solvent, temperature, pH, and reaction time are varied depending upon the lipase and target compounds of Formula I.
In an embodiment, the coupling agent is selected from a group comprising 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC, EDAC or EDCI), hydroxybenzotriazole(HOBt), 2-(1H-Benzotriazole-1-yl)-1,1,3,3-tetramethylaminium tetrafluoroborate (TBTU), Hexafluorophosphate Benzotriazole Tetramethyl Uronium (HBTU), N,N'-Dicyclohexylcarbodiimide (DCC),(1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate, HexafluorophosphateAzabenzotriazoleTetramethylUronium (HATU),N,N'-Diisopropylcarbodiimide (DIC), N-Methylmorpholine (NMM).
In another embodiment, the pH of the reaction is maintained between 2 and 9; and the reaction temperature can vary between 0°C-150°C. The reaction time is varied between 2 to 72 hours or till completion of the reaction.
In another embodiment, the solvent for the reaction is selected from protic or aprotic solvents or its combination in appropriate ratio; wherein the protic solvents are water, methanol, ethanol, and isopropyl alcohol; and aprotic solvents are Methyl tert-butyl ether, dichloromethane, ethyl acetate, acetone, dimethyl formamide, and tetrahydrofuran.
EXAMPLES:
A. For the purpose of exemplification of present invention following example of preparation of compound of Formula I and its salt through compound of Formula 1-d and Formula II, wherein “n”, “l” and “m” is 1 and invention is not restricted to below example.
The schematic representation of the preparation of compound of Formula I and salt thereof.

Scheme-B
Example 1: 4-{[(3R,5S)-1-(11-{[1,3-bis(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2-yl]oxy}pentanamido)propyl] carbamoyl}ethoxy)-2-[(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2-yl]oxy}pentanamido) propyl] carbamoyl}ethoxy)methyl]propan-2-yl]carbamoyl}undecanoyl)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}pyrrolidin-3-yl]oxy}-4-oxobutanoic acid (Formula I).
Step 1: Preparation of (3R,5S)-5-{[bis(4-methoxyphenyl) (phenyl)methoxy]methyl}-1-[(9H-fluoren-9-ylmethoxy)carbonyl]pyrrolidin-3-yl 1-prop-2-en-1-yl butanedioate (2).

To a solution of allyl succinate (6.4 g, 40.51 mmol) in dichloromethane (130 mL) were added EDCI.HCl (7.73 g, 40.51 mmol), N,N-diisopropylethylamine (7.06 mL, 40.51 mmol), 4-dimethylaminopyridine (0.24 g, 2.02 mmol) and 9H-fluoren-9-ylmethyl(2S,4R)-4-hydroxy-2-({[(4-hydroxyphenyl)(4methoxyphenyl) benzyl] oxy}methyl) pyrrolidine-1-carboxylate 1 (13.0 g, 20.25 mmol) at 0-5°C and the resulting reaction mixture is stirred for 4 h at temperature ranging from about 20-35°C. The resulting reaction mass was diluted with ethyl acetate (300 mL) and washed with 5% ammonium chloride solution (100 mL), saturated NaHCO3 solution (100 mL) and brine solution (150 mL). The organic layer was dried over Na2SO4, filtered and filtrate was concentrated under reduced pressure at 35 °C. The crude product obtained upon evaporation of volatiles was washed with hexanes to obtain 2 as a brown wax 14.0 g (86%).
Step 2: Preparation of (3R, 5S)-5-{[bis(4-methoxyphenyl) (phenyl) methoxy] methyl}pyrrolidin-3-yl1-prop-2-en-1-yl butanedioate (3).

To a solution of (3R,5S)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}-1-[(9H-fluoren-9-ylmethoxy)carbonyl]pyrrolidin-3-yl 1-prop-2-en-1-yl butanedioate 2 (14 g, 17.9 mmol) in dichloromethane (140 mL) was added piperidine (14.0 mL, 1V) and the resulting reaction mixture was stirred for 16 h at temperature ranging from about 20-35°C.. The resulting reaction mass was diluted with ethyl acetate (300 mL) and washed with water (150 mL X 2). The organic layer was dried over Na2SO4, filtered and filtrate was evaporated under reduced pressure at 30-35 °C. The crude product obtained upon evaporation of volatiles was washed with hexanes to obtain 3 as a brown wax 8.0 g (80%).
Step 3: Preparation of12-[(2S,4R)-2-{[bis(4-methoxyphenyl)(phenyl) methoxy] methyl}-4-{[4-oxo-4-(prop-2-en-1-yloxy)butanoyl]oxy}pyrrolidin-1-yl]-12-oxododecanoic acid (4)
To a solution of dodecanedioic acid (2.88 g, 12.50 mmol) in dichloromethane (30 mL) were added EDC.HCl (2.38 g, 12.50 mmol), N,N-diisopropylethylamine (4.36 mL, 25.01 mmol), 4-dimethylaminopyridine (0.15 g, 1.25 mmol) and (3R,5S)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}pyrrolidin-3-yl 1-prop-2-en-1-yl butanedioate 3 (3.5 g, 6.25 mmol) at 0-5 °C. Allowed the reaction mixture to stir for 4 h at ranging from about 20-35°C. The resulting reaction mass was diluted with ethyl acetate (300 mL), washed with 5% ammonium chloride solution (100 mL), saturated NaHCO3 solution (100 mL) and brine solution (150 mL). The organic layer was dried over Na2SO4, filtered and filtrate was concentrated under reduced pressure at 30-35 °C. The crude product obtained upon evaporation of volatiles was purified through silica gel (neutralized with triethylamine) column chromatography (gradient: 4-5% DCM/MeOH) to obtain 4 as a pale brown wax 3.0 g (55 %).

Step 4: Preparation of (3R,5S)-1-(11-{[1,3-bis(2-{[3-(5-{[4,5-bis(acetyloxy)-6-[(acetyloxy) methyl]-3 – acetamidooxan-2yl]oxy}pentanamido)propyl] carbamoyl}ethoxy)-2-[(2-{[3-(5-{[4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2-yl]oxy}pentanamido)propyl] carbamoyl}ethoxy)methyl]propan-2-yl]carbamoyl}undecanoyl)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy] methyl}pyrrolidin-3-yl1-prop-2-en-1-ylbutanedioate (6)

To a solution of 12-[(2S,4R)-2-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}-4-{[4-oxo-4-(prop-2-en-1-yloxy) butanoyl]oxy}pyrrolidin-1-yl]-12-oxododecanoic acid 4 (0.25 g, 0.28 mmol) in DMF (1 mL) were added HBTU (0.11 g, 0.30 mmol), N,N-diisopropylethylamine (0.2 mL, 1.14 mmol) and 5 (0.54 g, 0.28 mmol) at 0-5°C. The resulting reaction mixture was allowed to stir for 16 h at ranging from about 20-35°C. The reaction mass was diluted with ethyl acetate (150 mL), washed with 5% ammonium chloride solution (60 mL), saturated NaHCO3 solution (60 mL) and brine solution (100 mL). The organic layer was dried over Na2SO4, filtered and filtrate was concentrated under reduced pressure at 30-35 °C. The crude product obtained upon evaporation of volatiles was re-precipitated with DCM/Hexanes and dried over high vacuum to obtain 6 as an off white solid 0.41 g (50%).
Step 5: Preparation of 4-{[(3R,5S)-1-(11-{[1,3-bis(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2-yl]oxy}pentanamido)propyl]carbamoyl}ethoxy)-2-[(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3 –acetamidooxan-2-yl]oxy}pentanamido)propyl]carbamoyl}ethoxy)methyl]propan-2-yl]carbamoyl}undecanoyl)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}pyrrolidin-3-yl]oxy}-4-oxobutanoic acid; triethylamine (7).

Procedure A:-
To a solution of 6 (0.2 g, 1 eq.) in PBS buffer (pH=7.4)/acetone (1:2, 5V) was added Lipase (0.04 g, 20% by weight) at 20-35 °C. The reaction mixture was allowed to stir for 72 hrsat 20-35 °C. The completion of the reaction was monitored by TLC. The reaction mass was concentrated to dryness under reduced pressure at 30-35 °C. The residue obtained was diluted with DCM (15V) and stirred for 20 minutes. The solid precipitate (Lipase) was removed by filtration and filtrate was allowed to stir for 30 min with triethylamine (3 eq). The solvent was evaporated under reduced pressure and the residue obtained was re-precipitated with DCM/MTBE and dried over high vacuum to obtain 7 as an off white low melting solid 0.14 g (70%).
Procedure B:-
To an ice cooled solution of 6 (0.2 g, 0.078 mmol) in dry THF (2 mL, 10V), was added Pd(PPh3)4 (0.009 g, 0.0078mmol) followed by pyrrolidine (0.006 mL, 0.0078 mmol) and the resulting reaction mixture was allowed to stir for 2h. The reaction mass was concentrated to dryness under reduced pressure at 30-35 °C. The residue obtained was diluted with DCM (5V), filtered through celite and the filtrate was stirred with excess of triethylamine for 20 minutes. The solvent was evaporated under reduced pressure and the residue obtained was re-precipitated with DCM/MTBE and dried over high vacuum to obtain 7 as an off white low melting solid 0.12 g (60%).

Scheme- B
Example 2:
Step 1: Preparation of 1-benzyl (3R,5S)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}-1-[(9H-fluoren-9-ylmethoxy) carbonyl]pyrrolidin-3-yl butanedioate (2).

To a solution of benzyl succinate (5.0 g, 24.01 mmol) in dichloromethane (100 mL) were added EDCI.HCl (4.6 g, 24.01 mmol), N,N-diisopropylethylamine (4.2 mL, 24.01 mmol), 4-dimethylaminopyridine (0.15 g, 1.2 mmol) and 9H-fluoren-9-ylmethyl (2S,4R)-4-hydroxy-2-({[(4-hydroxyphenyl)(4-methoxyphenyl)benzyl]oxy}methyl)pyrrolidine-1-carboxylate 1 (7.7 g, 12.0 mmol) at 0-5°C and the resulting reaction mixture is stirred for 4 h at temperature ranging from about 20-35°C. The resulting reaction mass was diluted with ethyl acetate (300 mL) and washed with 5% ammonium chloride solution (100 mL), saturated NaHCO3 solution (100) and brine solution (150 mL). The organic layer was dried over Na2SO4, filtered and filtrate was concentrated under reduced pressure at 35 °C. The crude product obtained upon evaporation of volatiles was washed with hexanes to obtain 2 as a brown wax 8.0 g (80%).
Step 2: Preparation of 1-benzyl (3R,5S)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy] methyl}pyrrolidin-3-yl butanedioate (3).

To a solution of 1-benzyl (3R,5S)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy] methyl}-1-[(9H-fluoren-9-ylmethoxy)carbonyl]pyrrolidin-3-yl butanedioate 2 (8 g, 9.61 mmol) in dichloromethane (80 mL) was added piperidine (8.0 mL, 1V) and the resulting reaction mixture was stirred for 16 h at temperature ranging from about 20-35 °C.. The resulting reaction mass was diluted with ethyl acetate (300 mL) and washed with water (150 mL X 2). The organic layer was dried over Na2SO4, filtered and filtrate was evaporated under reduced pressure at 30-35 °C. The crude product obtained upon evaporation of volatiles was washed with hexanes to obtain 3 as a brown wax 4.5 g (76%).
Step 3: Preparation of 12-[(2S, 4R)-4-{[4-(benzyloxy)-4-oxobutanoyl]oxy}-2-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}pyrrolidin-1-yl]-12-oxododecanoic acid (4)

To a solution of dodecanedioic acid (3.0 g, 13.0 mmol) in dichloromethane (30 mL) were added EDC.HCl (2.49 g, 13.0 mmol), N,N-diisopropylethylamine (4.55 mL, 26.0 mmol), 4-dimethylaminopyridine (0.16 g, 1.3 mmol) and 1-benzyl (3R,5S)-5-{[bis(4-methoxyphenyl)(phenyl)methoxy] methyl}pyrrolidin-3-yl butanedioate 3 (3.97 g, 6.51 mmol) at 0-5 °C. Allowed the reaction mixture to stir for 4 h at ranging from about 20-35 °C. The resulting reaction mass was diluted with ethyl acetate (300 mL), washed with 5% ammonium chloride solution (100 mL), saturated NaHCO3 solution (100 mL) and brine solution (150 mL). The organic layer was dried over Na2SO4, filtered and filtrate was concentrated under reduced pressure at 30-35 °C. The crude product obtained upon evaporation of volatiles was purified through silica gel (neutralized with triethylamine) column chromatography (gradient: 4-5% DCM/MeOH) to obtain 4 as a pale brown wax 3.0 g (56 %).
Step 4: Preparation of 1-benzyl (3R,5S)-1-(11-{[1,3-bis(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2yl]oxy}pentanamido) propyl]carbamoyl}ethoxy)-2-[(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2-yl]oxy}pentanamido) propyl]carbamoyl} ethoxy)methyl]propan-2-yl]carbamoyl}undecanoyl)-5-{[bis(4-methoxyphenyl) (phenyl)methoxy]methyl}pyrrolidin-3-yl butanedioate (6)

To a solution of 12-[(2S,4R)-4-{[4-(benzyloxy)-4-oxobutanoyl]oxy}-2-{[bis(4-methoxyphenyl)(phenyl)methoxy]methyl}pyrrolidin-1-yl]-12-oxododecanoic acid 4 (0.5 g, 0.6 mmol) in DMF (2 mL) were added HBTU (0.23 g, 0.6 mmol), N,N-diisopropylethylamine (0.42 mL, 2.4 mmol) and 5 (1.09 g, 0.6 mmol) at 0-5°C. The resulting reaction mixture was allowed to stir for 16 h at temperature ranging from about 20-35°C. The reaction mass was diluted with ethyl acetate (150 mL), washed with 5% ammonium chloride solution (60 mL), saturated NaHCO3 solution (60 mL) and brine solution (100 mL). The organic layer was dried over Na2SO4, filtered and filtrate was concentrated under reduced pressure at 30-35 °C. The crude product obtained upon evaporation of volatiles was re-precipitated with DCM/Hexanes and dried over high vacuum to obtain 6 as an off white solid 0.8 g (50%).
Step 5: Preparation of 4-{[(3R,5S)-1-(11-{[1,3-bis(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2-yl]oxy}pentanamido) propyl]carbamoyl}ethoxy)-2-[(2-{[3-(5-{[(2R,5R)-4,5-bis(acetyloxy)-6-[(acetyloxy)methyl]-3-acetamidooxan-2-yl]oxy}pentanamido)propyl]carbamoyl} ethoxy)methyl]propan-2-yl]carbamoyl}undecanoyl)-5-{[bis(4-methoxyphenyl) (phenyl)methoxy]methyl}pyrrolidin-3-yl]oxy}-4-oxobutanoic acid; triethylamine (7).

The substrate dibenzyl compounds (1 mmol), ammonium formate (3 mmol), 10% Pd/C (100 mg) and methanol (20 mL) were charged in to a 50 ml reactor. Reaction was stirred for 15-20 min at room temperature under nitrogen. After completion of the reaction (monitored by TLC) catalyst was removed by filtration, catalyst was washed with 5ml of methanol. The combined filtrate was concentrated to dryness. Then the residue was stirred with methyl tert-butyl ether and filtered to yield desired product.
Compound 6 (0.2 g, 1 eq.), 10% Pd/C (20 mg), methanol (10 mL) were charged into a parr hydrogenator vessel and allowed to shake for 6h under hydrogen (4 Kg pressure). After completion of the reaction (monitored by TLC) catalyst was removed by filtration, catalyst was washed with 5ml of methanol. The combined filtrate was concentrated to dryness. Then the residue was dissolved in DCM and stirred for 30 min with triethylamine (3 eq). The solvent was evaporated under reduced pressure and the residue obtained was re-precipitated with DCM/MTBE and dried over high vacuum to yield 7 as an off white low melting solid 0.12 g (60%).

It is to be understood that the present invention is susceptible to modifications, changes and adaptations by those skilled in the art. Such modifications, changes, adaptations are intended to be within the scope of the present invention.
,CLAIMS:
1. A compound of Formula 1-d:

1-d
Wherein R1 is selected from allyl, alkyl, aryl or arylalkyl groups;
Wherein the said group may be linear, branched, cyclic with or without being substituted with functional groups- selected from but not limited to halogens, nitro, amine, aldehyde, carbonyl, hydroxyl;
Wherein the said alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, tert-butyl;
aryl groups are phenyl, naphthyl groups;
aralkyl or substituted aralkyl are Benzyl, p-Methoxy benzyl;
“n” range from 0 to 15.

2. A process for preparing compounds of Formula 1-d comprising the steps of:

a. Reacting compound of Formula 1-a with mono succinyl esters to obtain compound of Formula 1-b;

b. Deprotecting the Fluorenylmethyloxycarbonyl (Fmoc) group from Formula 1-b to obtain a compound of Formula 1-c;

c. Coupling compound of Formula 1-c with dioic acids to obtain a compound of Formula 1-d.

3. The process as claimed in claim 2, wherein the reaction of Formula 1-a with mono-succinyl esters is carried out in a solvent selected from water, methanol, ethanol, isopropyl alcohol, Methyl tert-butyl ether, dichloromethane, ethyl acetate, acetone, dimethyl formamide, or tetrahydrofuran.

4. The process as claimed in claim 2, wherein the Fmoc deprotection is carried out using piperidine as a deprotecting agent.

5. The process as claimed in claim 2, wherein the coupling of Formula 1-c with dioic acids is performed using a coupling agent selected from 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC, EDAC or EDCI), hydroxybenzotriazole(HOBt), 2-(1H-Benzotriazole-1-yl)-1,1,3,3-tetramethylaminium tetrafluoroborate (TBTU), Hexafluorophosphate Benzotriazole Tetramethyl Uronium (HBTU), N,N'-Dicyclohexylcarbodiimide (DCC), (1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate, HexafluorophosphateAzabenzotriazoleTetramethylUronium (HATU), N,N'-Diisopropylcarbodiimide (DIC), or N-Methylmorpholine (NMM).

6. A process for preparing compounds of Formula II, comprising the steps of:

a. reacting compounds of Formula 1-d with compound of Formula 1-e

in the presence of a coupling reagent, to obtain compounds of Formula II.

Formula II
Wherein R1 is selected from allyl, alkyl, aryl or arylalkyl groups;
Wherein R2 is selected from alkyl, aryl, alkoxy, aryloxy or arylalkyl groups;
Wherein the said group may be linear, branched, cyclic with or without being substituted with functional groups- selected from but not limited to halogens, nitro, amine, aldehyde, carbonyl, hydroxyl;
Wherein the said alkyl groups are methyl, ethyl, propyl, isopropyl butyl, tert-butyl;
aryl groups are phenyl, naphthyl groups;
aralkyl or substituted aralkyl are Benzyl, p-Methoxy benzyl;
“l’ and “m” range from 0 to 5; and “n” range from 0 to 15.

7. The process as claimed in claim 6, wherein the coupling reagent is selected from 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC, EDAC or EDCI), hydroxybenzotriazole(HOBt), 2-(1H-Benzotriazole-1-yl)-1,1,3,3-tetramethylaminium tetrafluoroborate (TBTU), Hexafluorophosphate Benzotriazole Tetramethyl Uronium (HBTU), N,N'-Dicyclohexylcarbodiimide (DCC), (1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate, HexafluorophosphateAzabenzotriazoleTetramethylUronium (HATU), N,N'-Diisopropylcarbodiimide (DIC), N-Methylmorpholine (NMM).

8. A process of preparing compounds of Formula I and salts thereof comprising the steps of:

a. performing selective ester hydrolysis of compounds of Formula II using lipase to obtain compounds of Formula I and its salts.
or
b. conducting a palladium catalysed conversion of esters of Formula II to corresponding carboxylic acids of Formula I and its salts.

Formula I
Wherein R2 is selected from alkyl, aryl, alkoxy, aryloxy or arylalkyl groups;
Wherein the said group may be linear, branched, cyclic with or without being substituted with functional groups- selected from but not limited to halogens, nitro, amine, aldehyde, carbonyl, hydroxyl;
Wherein the said alkyl groups are methyl, ethyl, propyl, isopropyl butyl, tert-butyl;
aryl groups are phenyl, naphthyl groups;
aralkyl or substituted aralkyl are Benzyl, p-Methoxy benzyl;
“l’ and “m” range from 0 to 5; and “n” range from 0 to 15.
9. The process as claimed in claim 8, wherein the ester hydrolysis is performed at a temperature varying from 0°C to 150°C, at a pH between 2 and 9 and for a reaction time ranging from 2 to 72 hours or until the completion of the reaction.

10. The process as claimed in claim 9, wherein the ester hydrolysis is performed at a temperature ranging from 20°C to 35°C.

11. The process as claimed in claim 8, wherein the lipase is selected from the group consisting of crude, purified, and immobilized lipases listed in Table 1.

Sr.No Lipase name Sr.No Lipase name Sr.No Lipase name
1 Lipase CL “Amano’’ 29 SPRIN epobond THERMOLYSIN 57 Amano enzyme CES L-2
2 Lipase from porcine pancreas 30 Protease from Bacillus Licheniformis 58 Amano enzyme CES L-3
3 Lipase AY “Amano”30SD 31 Novozym 388 59 Amano enzyme CES L-4
4 Lipase R “Amano” 32 Lipex 100L 60 Amano enzyme CES L-5
5 Lipase A “Amano”12 33 Acylase "Amano" 61 Amano enzyme CES L-6
6 Lipase MER “Amano” 34 Esperase 8.0 L 62 Amano enzyme CES L-7
7 Lipase DF “Amano”15 35 Lipase AK "Amano" 20 63 AddzymeCalB
8 Newlase F 36 Protease N "Amano" 64 Addzyme TL
9 Lipase MH “Amano”10SD 37 Protease S "Amano" 65 Addzyme RD
10 Lipase G “Amano”50
Mono, Di-glyceride Lipase 38 Lipase AS "Amano" 67 Lipase MY
11 Lipase PS “Amano” 39 Lipase PS "Amano" SD 68 Lipase ALC
12 Lipase AK “Amano” 40 Neutrase 0.8 L 69 Lypolyve AN
13 Lipase PS ‘’Amano” IME 41 Savinase 16L, Type EX 70 Lypolyve CC
14 Novozym 435 (CALB lipase) 42 ASSEMBLASE liquid 71 Lipomod 34P-L034P
15 LipozymeTL IM 43 Lipase AY "Amano" 30SD-K 72 Lipomod 627P-L627P
16 Novozym 40086 44 Lipase MH "Amano" 10SD 73 Lipase F-DS
17 Lipozyme TL 100L 45 Lipase A "Amano" 12-K 74 Novolime (Novozymes)
18 Novocor AD L (CALA) 46 Lipase DF "Amano" 15-K 75 GreasexNovoCor AD (Novozymes)
19 Resinase HT 47 Papain from papaya latex, P3375-25G 76 Lipopan F (Novozymes)
20 Palatase 20000 L 48 Alcalase 77 Resinase
21 Novozym 51032 49 Trypsin from bovine pancreas cat: 93610 78 Noopazyme (Novozymes)
22 Subtilisin A 50 Lipase PS ‘’Amano” IME 79 CalB Lipase – Anthem
23 Alcalase 51 Lipase IME ( 90 ) 80 Lipase – Anthem
24 Savinase 52 Lipase IME ( 95 )
25 Esperase 53 Klietase
(amylase)
26 Neutrase 54 Amano enzyme CES NL-1
27 rTrypsin 55 Amano enzyme CES NL-2
28 SPRIN imibond THERMOLYSIN 56 Amano enzyme CES L-1

12. The process as claimed in claim 8, wherein the salt of the compound of Formula I is a triethylamine salt, prepared by reacting the compound of Formula I with triethylamine.