Claims:We Claim:

1. An improved process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula – I,

comprising steps of:

a) acylating beta-thymidine to obtain 2', 3'-diacetyl-beta-thymidine of formula (V);

b) oxidising 2', 3'-diacetyl-beta-thymidine to obtain 2', 3'-diacetyl-5-formyl-deoxyuridine of formula (IV);

c) treating 2', 3'-diacetyl-5-formyl-deoxyuridine of formula (IV) with melonic acid to obtain 2', 3'-diacetyl-deoxyuridine-5yl-acrylic acid of formula-(III);

d) brominating the 2', 3'-diacetyl-deoxyuridine-5yl-acrylic acid of formula-(III) with suitable brominating agent to obtain 2,3-diacetyl-(E)-5-(2-bromovinyl)-2’-deoxyuridine of formula (II); and

e) hydrolysing 2,3-diacetyl-(E)-5-(2-bromovinyl)-2’-deoxyuridine to obtain of (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula-(I)
2. The process according to the claim 1, wherein the acylating agent is selected from acetyl chloride or acetic anhydride.
3. The process according to the claim 1, wherein the acylation reaction is carried out in presence of solvent selected from the group consisting of N, N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylaminopyridine, 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 1,3-dimethylaminopyridine, 1,3-dimehtyl-2-imidazolinone and the combination thereof.
4. The process according to the claim 1, wherein the oxidation is carried out using oxidising agent selected from the group consisting of Jones reagent (sodium dichromate in aqueous sulfuric acid), pyridinium chlorochromate (PCC), pyridiniumdichromate, Collins reagent (the mixture of chromium trioxide with pyridine in dichloromethane), chromic acid, manganese dioxide, Swern oxidation agent (oxalyl chloride and dimethyl sulfoxide), potassium permanganate, sodium persulfate, potassium persulfate and a combination of copper sulfate and 2, 6-lutidine.
5. The process according to the claim 1, wherein the reaction of 2', 3'-diacetyl-5-formyl-deoxyuridine of formula (IV) with melonic acid is carried out in the presence of base selected from triethylamine, pyridine, piperidine, dimethylaminopyridine and combination thereof.
6. The process according to the claim 1, wherein bromination of 2', 3'-diacetyl-deoxyuridine-5yl-acrylic acid of formula-(III) is carried out by brominating agent selected from bromine, hydrogen bromide, N-bromosuccinimide, sodium bromide, cyanogen bromide1,3-dibromo-5,5-dimethyl hydantoin, 2,4,4,6-tetrabromo-2,5-cyclohexadien-1-one and combination thereof.
7. The process according to the claim 1, wherein the hydrolysis is carried out by base selected from group consisting of sodium hydroxide, potassium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate and combination thereof.

Dated this (20th) day of August 2021
for Nuray Chemicals Private Limited

Dr. K. Ravi
Technical Director and Unit Head
, Description:FORM 2

THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003

COMPLETE SPECIFICATION

IMPROVED PROCESS FOR THE PREPARATION OF (E)-5-(2-BROMOVINYL)-2'-DEOXYURIDINE

Nuray Chemicals Private Limited
Plot No. 111, SIDCO Industrial Estate,
Kakkalur, Thiruvallur District,
Tamil Nadu, India 602003

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

FIELD OF THE INVENTION

The present invention relates to an improved process for the preparation of (E)-5-(2-bromovinyl)-2'-deoxyuridine.

BACKGROUND OF THE INVENTION

(E)-5-(2-Bromovinyl)-2’-deoxyuridine is an analogue of the nucleoside thymidine with high and selective antiviral activity against varicella zoster virus and herpes simplex virus. (E)-5-(2-bromovinyl)-2’-deoxyuridine is approved antiviral drug for mainly treating herpes zoster. (E)-5-(2-bromovinyl)-2’-deoxyuridine is a uridine derivative and nucleoside analog with pro-apoptotic and chemosensitizing properties. In vitro, (E)-5-(2-bromovinyl)-2’-deoxyuridine has been shown to downregulate the multifunctional DNA repair enzyme APEX nuclease 1, resulting in the inhibition of DNA repair and the induction of apoptosis. In addition, this agent may inhibit the expression of STAT3 (signal transducer and activator of transcription 3), which may result in the downregulation of vascular endothelial growth factor (VEGF). (E)-5-(2-bromovinyl)-2’-deoxyuridine has also been found to inhibit the upregulation of chemoresistance genes (Mdr1 and DHFR) during chemotherapy. Overall, the gene expression changes associated with BVDU treatment result in the decrease or prevention of chemoresistance. In addition, this agent has been shown to enhance the cytolytic activity of NK-92 natural killer cells towards a pancreatic cancer cell line in vitro.

(E)-5-(2-bromovinyl)-2’-deoxyuridine is also useful to inhibit the upregulation of chemoresistance genes (Mdr1 and DHFR) during chemotherapy. Overall, the gene expression changes associated with (E)-5-(2-bromovinyl)-2’-deoxyuridine treatment result in the decrease or prevention of chemoresistance. In addition, it has been shown to enhance the cytolytic activity of NK-92 natural killer cells towards a pancreatic cancer cell line in vitro.

GB 1601020A patent is first disclosed the (E)-5-(2-bromovinyl)-2’-deoxyuridine of formula (I). This patent described a process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine of formula (I) by alkylation of E-5-(2-bromovinyl) uracil with 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-a-D-erythro-pentofuranose followed by deacylation using sodium methoxide. The major disadvantages associated in this patent process include the use of expensive starting material, industrially not suitable chromatographic purification methods to remove the unwanted excess of a-isomer formed in the reaction and use carcinogenic reagent such as bromine in the bromination step which make this process not suitable in commercial scale.

GB 2125399 describes another process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine involves the bromination and simultaneous dehydrohalogenation of 5-ethyl-2’-deoxyuridine in the presence of halogenated hydrocarbon solvent. The process is depicted in the below as Scheme- I:

The major disadvantage associated with the process disclosed in this patent includes the use of bromine for bromination, which make the process carcinogenic and its own handling issue in commercial scale.

US 2010298530 A1 discloses a process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine by coupling 5-Iodo deoxyuridine with methyl acrylate in presence of palladium acetate to form (E)-5-(carbomethoxyvinyl)-2’-deoxyuridine, which is hydrolyzed with sodium hydroxide solution to obtain (E)-5-(carboxyvinyl)-2’-deoxyuridine, which undergoes bromination by using N-Bromo succinimide [NBS] to obtain (E)-5-(2-bromovinyl)-2’-deoxyuridine. The process is depicted in the below as Scheme – II:

The major disadvantages associated in this process include the use of expensive palladium acetate as catalyst, chromatographic purification method and use of hazardous reagent such as methyl acrylate and liberation of iodine from the reaction which is making this process is not suitable for industrial scale.

EP1363928 B1 disclosed process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine (I) starting from 3’,5’-di-O-p-chlorobenzoyl-5-ethyl-2’-deoxyuridine. The starting material used in this reaction is not cost effective and it is not easily obtainable from commercial sources which makes this process is industrially viable.

The present inventors surprisingly found an alternative and industrial feasible process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine (I) using inexpensive and potentially non-hazardous raw materials. The present process also minimizing the formation of undesired a-isomer and the other process related impurities. The present invention directed towards a process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula – I with high purity and high yield.

OBJECTIVE OF THE INVENTION

The main objective of the present invention is to provide an improved process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula–I or pharmaceutically acceptable salts thereof.

Another objective of the present invention is to provide, an improved process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine which is cost effective and industrially viable.

SUMMARY OF THE INVENTION

In an embodiment, the present invention provides an improved process for the preparation of (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula – I, which comprises:
a) acylating beta-thymidine to obtain 2', 3'-diacetyl-beta-thymidine of formula (V);
b) oxidising 2', 3'-diacetyl-beta-thymidine to obtain 2', 3'-diacetyl-5-formyl-deoxyuridine of formula (IV);
c) treating 2', 3'-diacetyl-5-formyl-deoxyuridine of formula (IV) with melonic acid to obtain 2', 3'-diacetyl-deoxyuridine-5yl-acrylic acid of formula-(III);
d) brominating the 2', 3'-diacetyl-deoxyuridine-5yl-acrylic acid of formula-(III) with suitable brominating agent to obtain 2,3-diacetyl-(E)-5-(2-bromovinyl)-2’-deoxyuridine of formula (II); and
e) hydrolysing 2,3-diacetyl-(E)-5-(2-bromovinyl)-2’-deoxyuridine to obtain of (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula-(I)

The present invention is illustrated in the following scheme

Detailed Description of the Invention

In an embodiment of the present invention, the acylating agent in step a) is selected from acetyl chloride or acetic anhydride and this reaction carried out from suitable solvent selected from the group consisting of N, N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylaminopyridine, 1-methyl-2-pyrrolidone, 1-methyl-2-piperidone, 1,3-dimethylaminopyridine, 1,3-dimehtyl-2-imidazolinone and combination thereof.

In another embodiment of the present invention, the oxidation is carried out using Jones reagent (sodium dichromate in aqueous sulfuric acid), pyridinium chlorochromate (PCC), pyridiniumdichromate, Collins reagent (the mixture of chromium trioxide with pyridine in dichloromethane), chromic acid, manganese dioxide, Swern oxidation agent (oxalyl chloride and dimethyl sulfoxide), potassium permanganate, sodium persulfate, potassium persulfate and combination of copper sulfate and 2,6-lutidine.

In another embodiment of the present invention, the reaction of 2', 3'-diacetyl-5-formyl-deoxyuridine of formula (IV) with melonic acid is carried out in the presence of base selected from triethylamine, pyridine, piperidine, dimethylaminopyridine and combination thereof.

In another embodiment of the present invention, 2', 3'-diacetyl-deoxyuridine-5yl-acrylic acid of formula-(III) is brominated by brominating agent selected from bromine, hydrogen bromide, N-bromosuccinimide, sodium bromide, cyanogen bromide, 1,3-dibromo-5,5-dimethyl hydantoin, 2,4,4,6-tetrabromo-2,5-cyclohexadien-1-one and combination thereof.

In another embodiment of the present invention, the hydrolysis is carried out by base selected from group consisting of sodium hydroxide, potassium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate and combination thereof.

The starting material used in the present invention is prepared by conventional methods.
The present invention is provided by the examples below, which are provided by way of illustration only and should not be considered to limit the scope of this invention.

Example 1: Process for the preparation of 2', 3'-diacetyl-beta-thymidine
To a dichloromethane 500 g of ß-thymidine was added under stirring. To the mass 752 g of triethylamine was added, stirred followed by added at 25-35 °C. The reaction mass was cooled to 10 °C, 527 g of acetic anhydride was added, heated to 25-35 °C. After completion of the reaction the reaction mass was cooled and washed with water. The layers were separated, the organic layers was treated with 5% HCl solution and repeat two times this operation. The layers were separated; to the organic layer 500 g of water was added, stirred and settled. The organic layer was distilled completely at 35-40 °C under atm pressure followed by vacuum. To the mass 100 g of isopropanol was added and distilled completely at 35-40 °C and washed with isopropanol and filtered. The obtained solid was washed with 393 g of isopropanol, spin dried and then dried under vacuum at 40-45 °C for 7 hrs.

Example 2: Preparation of 2', 3'-diacetyl-5-formyl-deoxyuridine of Formula (IV)
To a solution of 300 g of water, 16.5 g of copper sulfate pentahydrate and potassium persulfate were added at 45-55 °C, stirred and heated to 55 °C. To the reaction mass, mixture of stage-1 solution in acetonitrile and 2, 6-Lutudine were added at 50 °C and stirred for 90 min. After completion of the reaction, the reaction mass was cooled to 30 °C, filtered and bed was washed with acetonitrile. To the filtrate ethyl acetate was added, stirred at 10 °C for 10 minutes and settled the mass. The layers were separated and the combined organic layers were treated with 100 g of 8% sodium bicarbonate solution and layers were separated. The combined aqueous layers were treated with ethylacetate and was distilled and cooled to 25-35 °C. To the mass 86.g of 1, 4-dioxane was added at 25-35 °C and stirred for 10-15 °C.

Example 3: Preparation of 2', 3'-diacetyl-deoxyuridine-5yl-acrylic acid of formula-(III)
To the above reaction mixture 86 g of 1, 4-dioxane was added. To the reaction mass 17.5 g of malonic acid and 0.1V of piperidine were added, stirred for 10 mins, heated to 90 ºC and maintained for 12 h. After completion of the reaction, the reaction mass was cooled to 50 ºC, distilled under vacuum at 50 ºC and then cooled to room temperature. To the mass 4V of dichloromethane was added, stirred and treated with 8% sodium bicarbonate solution, stirred at 10 ºC and settled. The layers were separated and repeat the above process two times in the organic layer. To the combined aqueous layers was added 2V of dichloromethane, stirred at 10 ºC for 10 min. and allowed to settle the mass. The layers were separated and the aqueous layer was added 2V of dichloromethane, stirred at 10 ºC for 10 min. and allowed to settle the mass. The layers were separated, the aqueous layer was cooled to 10 ºC, and pH was adjusted to 1.0 to 2.0 using dilute HCl solution. To the reaction mass 0.5V ethyl acetate was added, stirred for 6 hours, filtered and suck dried. The solid was washed with water, suck dried and dried under vacuum at 50 ºC.

Example 4: (E)-5-(2-bromovinyl)-2’-deoxyuridine of formula (II)
To a 100 mL of dichloromethane 10 g of (E)-5-(2-bromovinyl)-2’-deoxyuridine of formula (II) was added stirred for 5 min at 25 ºC. To the reaction mass, 3g of triethylamine was added, stirred and N-bromosuccinimide (NBS) was added and maintained for 2hrs. After completion for the reaction 50 mL of water was added at 25-35 ºC, stirred for 5 minutes and allowed to settle. Layers were separated and 50 mL of water was added to the organic layer, stirred and allowed to settle. The organic layer was separated and washed with 5% HCl solution, layers were separated.

Example 5: Process (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula-(I)
The organic layers obtained from previous example was added to sodium hydroxide solution and stirred for 60 minutes. After completion of the reaction, the mass was allowed to settle and separated organic layer was kept aside. To the aqueous layer 50 mL of dichloromethane was added, stirred for 10 min, allowed to settle and layers were separated. To the aqueous layer 50 mL of dichloromethane was added, stirred for 10 min, allowed to settle and layers were separated. To the aqueous layer 5 mL acetonitrile was added, pH was adjusted 5.5-6.5 using 50% HCl solution and suck well. The wet cake was added to water heated to 65 ºC, The reaction mass was stirred for 10 min. cooled to 30 minutes, stirred for 60 min and filtered the solid. The solid was washed with water, suck dried and dried under vacuum at 50 ºC to obtain (E)-5-(2-bromovinyl)-2’-deoxyuridine of Formula-(I)
.

Dated this (20th) day of August 2021
for Nuray Chemicals Private Limited

Dr. K. Ravi
Technical Director and Unit Head