DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2006
COMPLETE SPECIFICATION
(See Section 10; rule 13)

“NOVEL PROCESS FOR THE PREPARATION OF DIFELIKEFALIN ACETATE”

Applicant : NEULAND LABORATORIES LIMITED
Nationality : India
Address : Neuland Laboratories Limited, 11th Floor, 5th Office Level,
Plot No. 573A-III, Phoenix IVY Building, Road No.82,
Jubilee Hills, Hyderabad-500033, Telangana, India.

The following specification particularly describes nature of the invention and manner in which it is to be performed.

Title of The Invention
Novel process for the preparation of Difelikefalin Acetate.

Field of The Invention
The present invention relates to the novel process for the preparation of Difelikefalin Acetate having the chemical Formula I.

Background of the Invention
Difelikefalin Acetate (Korsuva) is an analgesic opioid peptide used for the treatment of moderate-to-severe pruritus. It acts as a peripherally specific, highly selective agonist of the ?-opioid receptor (KOR).

Difelikefalin Acetate was approved for medical use in the United States on August 2021, in the Japan on Sep 2023 and sold under the brand name KORSUVA. In the European Union on April 2022 and sold under the brand name KAPRUVIA.

Difelikefalin Acetate and its process for the preparation is first disclosed in US 7,402,564 B1. In this process, there is a possibility of formation of several impurities which shows impact on yield as well as purity of final API and additional purification techniques required to obtain pure Difelikefalin Acetate. This process is highly expensive.

Several process for the preparation of Difelikefalin Acetate and its fragments has been disclosed in US 7,842,662 B2, US 8,536,131 B2 and CN 108883185 B. These processes have several disadvantages with lot of technical difficulties, expensive production costs and not suitable for large scale production due to complex purification methods.

In view of all these disadvantages, there is a significant need to develop a cost effective, stable, commercially viable, large scale and robust process for the preparation of highly pure Difelikefalin Acetate with good yield.

Summary of The Invention
In one aspect, the present invention relates to the novel process for the preparation of Difelikefalin Acetate compound of Formula I by using unprotected alpha amino acids in liquid phase synthesis,

which comprises:
i. activation of N-protected-D-Phe-OH in presence of activating agent in a solvent or mixture of solvents; wherein N-protected is Boc or Cbz (Z)
ii. coupling of H-D-Phe-OH to the N-protected-D-Phe-OSu active ester obtained in step-i) in presence of coupling agent in a solvent to obtain N-protected-D-Phe-D-Phe-OH dipeptide;
iii. sequential activation and coupling of H-D-Leu-OH, H-D-Lys(P)-OH and P-Pip-OH to the obtained dipeptide in step-ii) in presence of coupling agent and solvent to obtain protected Difelikefalin;
iv. global deprotection of Difelikefalin in presence of acid and solvent to obtain Difelikefalin HCl; and
v. purification of Difelikefalin HCl in presence of ammonium acetate, purified water and acetonitrile and followed by salt exchange with acetic acid to obtain Difelikefalin Acetate.

In another aspect, the present invention also relates to a novel process for the preparation of Difelikefalin Acetate compound of Formula I by using unprotected alpha amino acids in liquid phase synthesis,

which comprises:
i. activation of N-protected-D-Phe-OH in presence of activating agent in a solvent or mixture of solvents;
wherein N-protected is Boc or Cbz (Z);
ii. coupling of H-D-Phe-OH to the N-protected-D-Phe-OSu active ester obtained in step-i) in presence of coupling agent in a solvent to obtain N-protected-D-Phe-D-Phe-OH dipeptide;
iii. sequential activation and coupling of H-D-Leu-OH, H-D-Lys(P)-OH and P-Pip-OH to the obtained dipeptide in step-ii) in presence of a coupling agent and solvent to obtaine protected Difelikefalin;
iv. N-terminal debenzylation followed by global deprotection of Difelikefalin in presence of acid and solvent to obtain Difelikefalin HCl;
v. purification of Difelikefalin HCl in presence of ammonium acetate, purified water and acetonitrile and followed by salt exchange with acetic acid to obtain Difelikefalin Acetate.

Detailed Description of the Invention
The present invention involves using unprotected alpha amino acids as building blocks for the preparation of Difelikefalin Acetate by making appropriate amino acid in required sequence in liquid phase approach with higher yields and purity.

Activating agent used throughout the invention is selected from the group consisting of HOSu, PFP, Trizene, Chloro formate or mixture thereof.

Solvents used throughout the invention is selected from the group consisting of alcoholic solvents such as methanol, ethanol, isopropanol; chlorinated solvents such as chloroform, methylene chloride; ester solvents such as ethyl acetate, butyl acetate, isopropyl acetate; ether solvents such as diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, diisopropyl ether, Methyl tert-butyl ether; nitrile solvents such as acetonitrile; aprotic solvents and protic solvents such as dimethylformamide, dimethyl sulfoxide, dimethylacetamide, 1,4-dioxane, N-Methyl-2-pyrrolidone, acetone, hexane, heptane, water or a mixture thereof.

Coupling reagents used throughout the invention is selected from the group consisting of N,N'-Diisopropylcarbodiimide, Dicyclohexyl carbodiimide, 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide.HCl, 1-Hydroxybenzotriazole, 1-Hydroxy-7-azabenzotriazole, Ethyl cyanohydroxyiminoacetate (Oxyma) or mixture thereof.

Coupling of amino acid is carried out in presence of a base or without using a base. The base is organic or inorganic base. The inorganic base is selected from the group consisting of potassium carbonate, lithium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide and mixture thereof; the organic base is selected from the group consisting of diisopropyl amine, N,N-diisopropyl ethylamine, triethylamine, tertiary butyl amine, dimethylamine, tri methyl amine, isopropyl ethylamine, pyridine, piperidine, N-methyl morpholine or mixture thereof.

In one embodiment, the present invention involves a novel process for the preparation of Difelikefalin Acetate by assembling appropriate unprotected alpha amino acid in liquid phase in a required sequence. Followed by global deprotection and purification on reverse phase HPLC, freeze drying and isolation to get pure Difelikefalin Acetate. The schematic description of the process is as shown in Scheme-I.

Scheme I

In step-i), N-Protected-D-Phe-OH, dichloromethane, tetrahydrofuran, dimethylformamide and HOSu was taken in RB flask and add di-cyclohexyl carbodiimide to the above reaction mixture in tetrahydrofuran to obtain N-Protected-D-Phe-Osu active ester of compound.

The reaction temperature may range from 5 °C to 30 °C and preferably at a temperature in the range from 25°C to 30 °C. The duration of the reaction may range from 3 hours to 5 hours, preferably for a period of 4 hours.

In step-ii), coupling of N-Protected-D-Phe-Osu active ester with H-D-Phe-OH in presence of coupling agent and solvent to obtain dipeptide, which is further activation followed by sequential coupling of active ester with H-D-Leu-OH, H-D-Lys(Boc)-OH and P-Pip-OH in presence of coupling agent and solvent to obtain protected Difelikefalin.

The coupling agent used in this step is DIC, DCC, Oxyma pure in dimethylformamide and EDC. HCl.

The reaction temperature may range from 20 °C to 35 °C and preferably at a temperature in the range from 25°C to 30 °C. The duration of the reaction may range from 10 to 16 hours, preferably for a period of 12 hours.

In step-iii), global deprotection of protected Difelikefalin in presence of acid and solvent to obtain Difelikefalin HCl.

Reagent used in global deprotection is selected from the group consisting of 4M HCl in THF, TIPS, Water, DTT, Thioanisole, EDT, DMS, cresol, phenol, thiocresol, ammonium iodide, 2,2'-(ethylene dioxy)diethane, water or its mixture.

The reaction temperature may range from 0 °C to 5 °C and preferably at a temperature in the range from 5 °C to 10 °C. The duration of the reaction may range from 3 to 7 hours, preferably for a period of 3 to 6 hours.

In step-iv), purification of Difelikefalin HCl in presence of ammonium acetate, purified water and acetonitrile and followed by salt exchange with acetic acid to obtain Difelikefalin Acetate.

In another aspect, the present invention involves a novel process for the preparation of Difelikefalin Acetate by coupling appropriate unprotected alpha amino acid in liquid phase in a required sequence. Followed by N-terminal debenzylation, global deprotection and purification on reverse phase HPLC, freeze drying and isolation to get pure Difelikefalin Acetate. The schematic description of the process is as shown in Scheme-II.

Scheme II

In step-i), N-Protected-D-Phe-OH, dichloromethane, tetrahydrofuran, dimethylformamide and HOSu was taken in RB flask and add di-cyclohexyl carbodiimide to the above reaction mixture in tetrahydrofuran to obtain N-Protected-D-Phe-Osu active ester of compound.

The reaction temperature may range from 5 °C to 30 °C and preferably at a temperature in the range from 25°C to 30 °C. The duration of the reaction may range from 3 hours to 5 hours, preferably for a period of 4 hours.

In step-ii), coupling of N-Protected-D-Phe-Osu active ester with H-D-Phe-OH in presence of coupling agent and solvent to obtain dipeptide, which is further activation followed by sequential coupling of active ester with H-D-Leu-OH, H-D-Lys(Boc)-OH and P-Pip-OH in presence of coupling agent and solvent to obtain protected Difelikefalin.

The coupling agent used in this step is DIC, DCC, Oxyma pure in dimethylformamide and EDC. HCl.

The reaction temperature may range from 20 °C to 35 °C and preferably at a temperature in the range from 25°C to 30 °C. The duration of the reaction may range from 10 hours to 16 hours, preferably for a period of 12 hours.

In step-iii), N-terminal debenzylation followed by global deprotection of protected Difelikefalin in presence of acid and solvent to obtain Difelikefalin HCl.

Reagent used in global deprotection is selected from the group consisting of 4M HCl in THF, TIPS, Water, DTT, Thioanisole, EDT, DMS, cresol, phenol, thiocresol, ammonium iodide, 2,2'-(ethylene dioxy)diethane, water or its mixture.

The reaction temperature may range from 0 °C to 5 °C and preferably at a temperature in the range from 5 °C to 10 °C. The duration of the reaction may range from 3 to 7 hours, preferably for a period of 3 to 6 hours.

In step-iv), purification of Difelikefalin HCl in presence of ammonium acetate, purified water and acetonitrile and followed by salt exchange with acetic acid to obtain Difelikefalin Acetate.

While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention. The invention is illustrated below with reference to inventive and comparative examples and should not be construed to limit the scope of the invention.

EXPERIMENTAL PORTION
The details of the invention are given in the examples provided below, which are given to illustrate the invention only and therefore should not be construed to limit the scope of the invention.

Example 1: Synthesis of Difelikefalin Acetate.
Step-A: N-Protected-D-Phe-OH (5 grams), dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (2.4 grams) was taken in RB flask at room temperature to the above solution DCC (7.0 grams) was added in THF (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-Osu active ester (6.1 grams).

Step-B: H-D-Phe-OH (4.7 grams) was dissolved in sodium carbonate (2.6 grams) in purified water (60 mL) and stirred for 10 minutes. To this N-Protected-D-Phe-Osu active ester (6.1 grams) obtained from step-A was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain N-Protected-D-Phe-D-Phe-OH (6.3 grams).

Step-C: N-Protected-D-Phe-D-Phe-OH (6.3 grams) obtained from step-B was dissolved in dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (2.4 grams) at room temperature to the above solution DCC (5.7 grams) was added in THF (25 mL), MDC (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-D-Phe-Osu active ester (7.0 grams).

Step-D: H-D-Leu-OH (2.7 grams) was dissolved in sodium bicarbonate (1.3 grams) in purified water (60 mL) and stirred for 10 minutes and add a solution of N-Protected-D-Phe-D-Phe-Osu active ester (7.0 grams) obtained from step-C was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-OH (7.0 grams).

Step-E: N-Protected-D-Phe-D-Phe-D-Leu-OH (6 grams) obtained from step-D, dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (1.68 grams) at room temperature to the above solution DCC (4.2 grams) was added in THF (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-Osu active ester (6.3 grams).

Step-F: H-D-Lys(P)-OH (3.7 grams) was dissolved in sodium bicarbonate (1.0 gram) in purified water (60 mL) and stirred for 10 minutes and add a solution of N-Protected-D-Phe-D-Phe-D-Leu-Osu active ester (6.3 grams) obtained from step-E was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P)-OH (6.5 grams).

Step-G: N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P)-OH (6.5 grams) obtained from step-F was dissolved in dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (2.4 grams) at room temperature to the above solution DCC (3.0 grams) was added in THF (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P)-Osu active ester (6.28 grams).

Step-H: P-Pip-OH (2.6 grams) was dissolved in sodium bicarbonate (0.71 grams) in purified water (60 mL) and stirred for 10 minutes and add a solution of N-Protected-D-Phe-D-Phe-D-Leu- D-Lys(P)-Osu active ester (6.0 grams) obtained from step-G was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain P-Pip(N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P))-OH (6.1 grams).

Step-I: Global deprotection of P-Pip(N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P))-OH (6.0 grams) in presence of 4M hydrochloride in ethyl acetate (95 mL), tri-isopropyl silane (5 mL) at 5 °C to 10 °C and maintained for 4 to 6 hours. Then peptide precipitated in a mixture of purified water (7.5 mL) and acetone (75 mL) to obtain Difelikefalin Hydrochloride (5.5 grams).

Step-J: Difelikefalin Hydrochloride (5.5 grams) was dissolved in purified water (25 mL) and loaded onto preparative C18 column (50x250 mm, 120 A0). The peptide was purified using a linear gradient of 50 mm ammonium acetate (Buffer A) and acetonitrile: methanol (8:2) (Buffer B) from 5 % to 50% over 100 minutes. The pure fooled fraction was desalted by using Acetic acid buffer. The pooled pure fraction acetonitrile was evaporated and lyophilized to give the Difelikefalin Acetate as white solid. The resulting peptide was analysed by RP-HPLC and confirmed by MALDI or LC-MS.

Example 2: Synthesis of Difelikefalin Acetate.
Step-A: N-Protected-D-Phe-OH (5 grams), dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (2.4 grams) was taken in RB flask at room temperature to the above solution DCC (7.0 grams) was added in THF (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-Osu active ester (6.1 grams).

Step-B: H-D-Phe-OH (4.7 grams) was dissolved in sodium carbonate (2.6 grams) in purified water (60 mL) and stirred for 10 minutes and add a solution of N-Protected-D-Phe-Osu active ester (6.1 grams) obtained from step-A was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain N-Protected-D-Phe-D-Phe-OH (6.3 grams).

Step-C: N-Protected-D-Phe-D-Phe-OH (6.3 grams) obtained from step-B was dissolved in dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (2.4 grams) at room temperature to the above solution DCC (5.7 grams) was added in THF (25 mL), MDC (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-D-Phe-Osu active ester (7.0 grams).

Step-D: H-D-Leu-OH (2.7 grams) was dissolved in sodium bicarbonate (1.3 grams) in purified water (60 mL) and stirred for 10 minutes and add a solution of N-Protected-D-Phe-D-Phe-Osu active ester (7.0 grams) obtained from step-C was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-OH (7.0 grams).

Step-E: N-Protected-D-Phe-D-Phe-D-Leu-OH (6 grams) obtained from step-D, dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (1.68 grams) at room temperature to the above solution DCC (4.2 grams) was added in THF (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-Osu active ester (6.3 grams).

Step-F: H-D-Lys(P)-OH (3.7 grams) was dissolved in sodium bicarbonate (1.0 gram) in purified water (60 mL) and stirred for 10 minutes and add a solution of N-Protected-D-Phe-D-Phe-D-Leu-Osu active ester (6.3 grams) obtained from step-E was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P)-OH (6.5 grams).

Step-G: N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P)-OH (6.5 grams) obtained from step-F was dissolved in dichloromethane (25 mL), tetrahydrofuran (25 mL), dimethylformamide (25 mL) and HOSu (2.4 grams) at room temperature to the above solution DCC (3.0 grams) was added in THF (25 mL) at 5-10 °C over a period of 15-20 minutes then reaction was maintain for 2-3 hours at room temperature to obtain N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P)-Osu active ester (6.28 grams).

Step-H: P-Pip-OH (2.6 grams) was dissolved in sodium bicarbonate (0.71 grams) in purified water (60 mL) and stirred for 10 minutes and add a solution of N-Protected-D-Phe-D-Phe-D-Leu- D-Lys(P)-Osu active ester (6.0 grams) obtained from step-G was dissolved in acetone (6 mL) was slowly added at 5-10°C over a period of 15-20 minutes then reaction was maintain for 12-16 hours at the room temperature to obtain P-Pip(N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P))-OH (6.1 grams).

Step-I: N-terminal debenzylation P-Pip(N-Protected-D-Phe-D-Phe-D-Leu-D-Lys(P))-OH (6.1 grams) in presence of 4M hydrochloride in ethyl acetate (95 mL), tri-isopropyl silane (5 mL) at 5 °C to 10 °C and maintained for 4 to 6 hours. Then peptide precipitated in a mixture of purified water (7.5 mL) and acetone (75 mL) to obtain compound further deprotected in presence of 4M hydrochloride in ethyl acetate (95 mL), tri-isopropyl silane (5 mL) at 5 °C to 10 °C and maintained for 4 to 6 hours. Then peptide precipitated in a mixture of purified water (7.5 mL) and acetone (75 mL) to obtain Difelikefalin Hydrochloride (5.5 grams).

Step-J: Difelikefalin Hydrochloride Salt (5.5 grams) was dissolved in purified water (25 mL) and loaded onto preparative C18 column (50x250 mm, 120 A0). The peptide was purified using a linear gradient of 50 mm ammonium acetate (Buffer A) and acetonitrile: methanol (8:2) (Buffer B) from 5 % to 50% over 100 minutes. The pure fooled fraction was desalted by using Acetic acid buffer. The pooled pure fraction acetonitrile was evaporated and lyophilized to give the Difelikefalin Acetate as white solid. The resulting peptide was analysed by RP-HPLC and confirmed by MALDI or LC-MS.

Advantages of the present invention:
? The present invention eliminates Fmoc deprotection step.
? The present invention is economically significant and eco-friendly.
? The present invention reducing the purification time of preparative HPLC when compared to the prior-art process. ,CLAIMS:We claim:
1. A novel process for the preparation of Difelikefalin Acetate compound of Formula I by using unprotected alpha amino acids in liquid phase synthesis,

which comprises:
i. activation of N-protected-D-Phe-OH in presence of activating agent in a solvent or mixture of solvents; wherein N-protected is Boc or Cbz (Z);
ii. coupling of H-D-Phe-OH to the N-protected-D-Phe-OSu active ester obtained in step-i) in presence of coupling agent in a solvent to obtain N-protected-D-Phe-D-Phe-OH dipeptide;
iii. sequential activation and coupling of H-D-Leu-OH, H-D-Lys(P)-OH and P-Pip-OH to the obtained dipeptide in step-ii) in presence of coupling agent and solvent to obtained protected Difelikefalin;
iv. global deprotection of Difelikefalin in presence of acid and solvent to obtain Difelikefalin HCl;
v. purification of Difelikefalin HCl in presence of ammonium acetate, purified water and acetonitrile and followed by salt exchange with acetic acid to obtain Difelikefalin Acetate.

2. A novel process for the preparation of Difelikefalin Acetate compound of Formula I by using un protected alpha amino acids in liquid phase synthesis,

which comprises:
i. activation of N-protected-D-Phe-OH in presence of activating agent in a solvent or mixture of solvents; wherein N-protected is Boc or Cbz (Z);
ii. coupling of H-D-Phe-OH to the N-protected-D-Phe-OSu active ester obtained in step-i) in presence of coupling agent in a solvent to obtain N-protected-D-Phe-D-Phe-OH dipeptide;
iii. sequential activation and coupling of H-D-Leu-OH, H-D-Lys(P)-OH and P-Pip-OH to the obtained dipeptide in step-ii) in presence of a coupling agent and solvent to obtained protected Difelikefalin;
iv. N-terminal debenzylation followed by global deprotection in presence of acid and solvent to obtain Difelikefalin HCl;
v. purification of Difelikefalin HCl in presence of ammonium acetate, purified water and acetonitrile and followed by salt exchange with acetic acid to obtain Difelikefalin Acetate.

3. The process as claimed in claims 1 and 2, wherein said activating agent is selected from the group consisting of HOSu, PFP, Trizene, Chloro formate or mixture thereof.

4. The process as claimed in claims 1 and 2, wherein said coupling reagent is selected from the group consisting of N,N'-Diisopropylcarbodiimide (DIC), Dicyclohexyl carbodiimide (DCC), 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC).HCl, 1-Hydroxybenzotriazole (HOBT), 1-Hydroxy-7-azabenzotriazole (HOAT), Ethyl cyanohydroxyiminoacetate (Oxyma) or mixture thereof.

5. The process as claimed in claims 1 and 2, wherein said solvent is selected from the group consisting of methanol, ethanol, isopropanol, chloroform, methylene chloride, ethyl acetate, butyl acetate, isopropyl acetate, diethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diisopropyl ether (DIPE), Methyl tert-butyl ether (MTBE), acetonitrile, dimethylformamide, dimethyl sulfoxide, dimethylacetamide, 1,4-dioxane, N-Methyl-2-pyrrolidone (NMP), acetone, hexane, heptane, water or a mixture thereof.

6. The process as claimed in claims 1 and 2, wherein said deprotection reagent is selected from the group consisting of 4M HCl in THF, TIPS, Water, DTT, Thioanisole, EDT, DMS, cresol, phenol, thiocresol, ammonium iodide, 2,2'-(ethylene dioxy)diethane, water or its mixture.

Dated this 17th day of February 2025.
Signature:

Name: Dr. P.S.R.C. Murthy, Ph.D
Indian Patent Agent-2438
Director – IPR
Neuland Laboratories Limited.