Field of the Invention

The present invention provides an improved process for the preparation of bosutinib and its intermediate 2-cyano-/V-(2, 4-dichloro-5-methoxyphenyl)acetamide.

Background of the Invention

Bosutinib is chemically designated as 4-[(2,4-dichloro-5-methoxyphenyl)amino]- 6-methoxy-7-[3-(4-methyl-l-piperazinyl)propoxy]-3-quinolinec arbonitrile, as depicted by Formula I.

Formula I

U.S. Patent No. 6,002,008 and RE 42,376 disclose substituted 3-cyanoquinolines derivatives and preparation thereof.

U.S. Patent No. 7,297,795; Chinese Publication No. 102952037, and Indian Patent Application No. 3287/MUM/2014 disclose processes for the preparation of bosutinib and its intermediate 2-cyano-/V-(2,4-dichloro-5 -methoxyphenyl)acetamide .

There is a need for an alternate and improved process for the preparation of bosutinib and its intermediate 2-cyano-/V-(2,4-dichloro-5-methoxyphenyl)acetamide. The present invention provides an efficient and commercially useful process for the preparation of bosutinib via 2-cyano-/V-(2,4-dichloro-5-methoxyphenyl)acetamide intermediate.

Summary of the Invention

The present invention provides an improved process for the preparation of bosutinib and its intermediate 2-cyano-/V-(2, 4-dichloro-5-methoxyphenyl) acetamide. Detailed Description of the Invention

Various embodiments and variants of the present invention are described hereinafter.

The term“about,” as used herein, refers to any value which lies within the range defined by a variation of up to ± 10% of the value .

The term“treating,” as used herein, includes adding, dissolving, suspending, slurring, stirring, reacting, heating, cooling, condensing, or combinations thereof.

A first aspect of the present invention provides a process for the preparation of 2- cyano-/V-(2,4-dichloro-5-methoxyphenyl)acetamide of Formula II:

Formula II

comprising reacting cyanoacetic acid with 2,4-dichloro-5-methoxyaniline in the presence of oxalyl chloride.

In an embodiment of this aspect, the 2-cyano-/V-(2,4-dichloro-5-methoxyphenyl) acetamide of Formula II is further converted to bosutinib.

A second aspect of the present invention provides a process for the preparation of 2-cyano-/V-(2,4-dichloro-5-methoxyphenyl)acetamide of Formula II:

Formula II

comprising

i) treating cyanoacetic acid with oxalyl chloride;

ii) reacting the reaction mixture of step i) with 2,4-dichloro-5-methoxyaniline to obtain 2-cyano-/V-(2,4-dichloro-5-methoxyphenyl)acetamide.

In an embodiment of this aspect, the 2-cyano-/V-(2,4-dichloro-5-methoxyphenyl) acetamide of Formula II is further converted to bosutinib. 2,4-dichloro-5-methoxyaniline can be prepared by following the process described herein or the process disclosed in Synthesis 2015, 47, 3133-3138.

Cyanoacetic acid is treated with oxalyl chloride in the presence of a solvent at a temperature of about 0°C to about lO°C.

The solvent is selected from tetrahydrofuran, dimethylformamide,

dichloromethane, ethyl acetate, diethyl ether, diisopropyl ether, methyl ter-butyl ether, 1,4- dioxane or mixture thereof. The solvent is preferably selected from ethyl acetate and dimethylformamide or mixture thereof. The solvent is most preferably a mixture of ethyl acetate and catalytic amount of dimethylformamide.

The reaction of cyanoacetic acid and oxalyl chloride is carried out at a temperature of about 0°C to about lO°C, for example, at about 0°C to about 6°C.

The reaction of cyanoacetic acid and oxalyl chloride is carried out for about 90 minutes to about 150 minutes, for example, for about 120 minutes to about 130 minutes.

The reaction mixture obtained after treating cyanoacetic acid and oxalyl chloride is reacted with 2,4-dichloro-5-methoxyaniline under stirring.

The reaction with 2,4-dichloro-5-methoxyaniline is carried out at a temperature of about 20°C to about 70°C, for example, at about 23°C to about 65°C.

The reaction mixture is stirred for about 1 hour to about 4 hours, for example, for about 2 hours.

2-cyano-/V-(2,4-dichloro-5-methoxyphenyl)acetamide obtained is isolated.

2-cyano-N-(2,4-dichloro-5-methoxyphenyl)acetamide can be isolated by filtration, decantation, extraction, distillation, evaporation, chromatography, precipitation, concentration, crystallization, centrifugation, or recrystallization, and dried under reduced pressure, by air drying, or vacuum tray drying.

2-cyano-/V-(2,4-dichloro-5-methoxyphenyl)acetamide can be converted to bosutinib by following the process disclosed in U.S. Patent No. 7,297,795 or Journal of Medicinal Chemistry , 2001, 44 (23), 3965-3977.

The present invention provides 2-cyano-N-(2,4-dichloro-5- methoxyphenyl)acetamide with chromatographic (HPLC) purity of more than 99.6%. While the present invention has been described in terms of its specific aspects and 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 following example is for illustrative purpose only and should not be construed as limiting the scope of the invention in any way.

Method:

Chromatographic purity of the sample was determined by HPLC instrument using “Agilent HPLC with Non PDA detector and HPLC column Kromasil ^® C18 (150 x 4.6) mm, 5 pm.

The following example is for illustrative purposes only and should not be construed as limiting the scope of the invention in any way.

EXAMPLES:

Example 1 : Preparation of 2-CYano-N-(2.4-dichloro-5-methoxYphenyl)acetamide

Step-l : Preparation of 2.4-dichloro acetamidophenol:

Acetic acid (600 mL) and 3 -amino phenol (100 g) were charged into a flask at 20°C to 25 °C followed by addition of ammonium acetate (106 g) to obtain a reaction mixture. The reaction mixture was refluxed and stirred for 3 hours sulfuryl chloride (310 g) was added to the reaction mixture at 20°C to 25 °C slowly over a period of about 60 minutes and stirred at 20°C to 25°C for 3 hours. Deionized water (1000 mL) was added to the reaction mixture at 20°C to 25 °C drop wise over a period of about 30 minutes. The reaction mixture was stirred at 20°C to 25 °C for 2 hours. The solid was filtered and washed with deionized water (2500 mL). The wet solid was used as such in the next step.

Step-2: Preparation of 2.4-dichloro-5-methoxy acetamidophenol:

Potassium carbonate (285 g) was added to deionized water (750 mL) and mixture was stirred at 20°C to 25°C for about 10 minutes. 2,4-dichloro acetamidophenol (entire batch obtained from Step-l) was charged into acetone (450 mL) and stirred at 20°C to 25°C to get clear solution. Dimethyl sulphate (260 g) was added to the obtained solution at 20°C to 25 °C drop wise over a period of about 60 minutes. The reaction mixture was stirred at 20°C to 25 °C for about 3 hours. Deionized water (1000 mL) was added to the reaction mixture at 20°C to 25 °C slowly over a period of about 30 minutes. The reaction mixture was stirred at 20°C to 25 °C for 2 hours. The obtained solid was filtered and washed with deionized water (1000 mL). The wet solid was dried at 40°C to 45°C in air oven for approximately 12 hours to obtain the title product.

Yield: 145 g

Step-3: Preparation of 2.4-dichloro-5-methoxy aniline:

Methanolic hydrochloric acid (400 mL) was added into 2,4-dichloro-5-methoxy acetamidophenol (100 g, obtained from Step-2) at 25°C. The reaction mixture was heated to 50°C to 55°C and stirred for 3 hours. The reaction mixture was cooled to 25 °C and acetone (200 mL) was added. The reaction mixture was further cooled to -l0°C and stirred at -l0°C to 0°C for 2 hours. The solid obtained was filtered and washed with pre-cooled (0°C) acetone (100 mL). The wet solid was dried at 35°C to 40°C in air oven for approximately 12 hours to obtain the title product.

Yield: 80 g

Step-4: Preparation of 2-cvano-N-(2.4-dichloro-5-methoxyphenyl)acetamide:

Method A:

Cyanoacetic acid (50 g) was added to ethyl acetate (400 mL) at 25 °C followed by addition of dimethylformamide (2 mL). The obtained reaction mixture was cooled to 0°C and oxalyl chloride (82.6 g) was slowly added at 0°C to 5°C over a period of about 60 minutes. The temperature of the reaction mixture was raised up to 25°C to 28°C and stirred for 2 hours. 2,4-dichloro-5-methoxyaniline (100 g, obtained from Step-3) was added to the reaction mixture and heated up to 55°C to 60°C under stirring for about 2 hours. Deionized water (200 mL) was added to the reaction mixture at 20°C to 30°C followed by stirring for 1 hour. The product obtained was filtered and washed with ethyl acetate (50 mL) followed by deionized water (500 mL) and ethyl acetate (200 mL) respectively. The wet product was dried in air oven to provide the title product.

Yield: 97 g

Chromatographic Purity: 99.67% Method B:

Cyanoacetic acid (20 g) was added to ethyl acetate (200 mL) at 25 °C followed by addition of dimethylformamide (2.5 mL). The obtained reaction mixture was cooled to 2°C and oxalyl chloride (41.1 g) was slowly added at 2°C to 6°C over a period of 30 minutes. The temperature of reaction mixture was raised up to 23°C to 28°C and stirred for 2 hours. 2,4- dichloro-5-methoxyaniline (50.8 g, obtained from Step-3) was added to the reaction mixture and heated up to 62°C to 64°C under stirring for 2 hours. Deionized water (100 mL) was added to the reaction mixture at 20°C to 3 l°C followed by stirring for 45 minutes. The product obtained was filtered and washed with deionized water (250 mL) followed by ethyl acetate (50 mL). The wet product was dried under vacuum to provide the title product.

Yield: 93 g

Chromatographic Purity: 99.77 %