NEW PATENT, WOCKHARDT LIMITED, WO 2016055918, ISAVUCONAZOLE

WO2016055918) NOVEL STABLE POLYMORPHS OF ISAVUCONAZOLE OR ITS SALT THEREOF

WOCKHARDT LIMITED [IN/IN]; D-4, MIDC Area, Chikalthana, Aurangabad 431006 (IN)

KHUNT, Rupesh Chhaganbhai; (IN).
RAFEEQ, Mohammad; (IN).
MERWADE, Arvind Yekanathsa; (IN).
DEO, Keshav; (IN)

The present invention relates to novel stable novel stable polymorphs of Isavuconazole or its salt thereof, having purity more than 90 % when measured by HPLC. In particular the present invention directs process for the preparation of solid amorphous and crystalline form of Isavuconazole base. In a further embodiment present invention directs to crystalline form Isavuconazole Hydrobromide salt and oxalate salt of 2-(2,5-difluoro- phenyl)-1-[1,2,4]triazol-1-yl-butane-2,3-diol.

Isavuconazole, Isavuconazonium, Voriconazole, and Ravuconazole are azole derivatives and known as antifungal drugs for treatment of systemic mycoses as reported in US 5,648,372, US 5,792,781, US 6,300,353 and US 6,812,238.

The US patent No. 6,300,353 discloses Isavuconazole and its process. It has chemical name [(2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl)]-l -(lH-l,2,4-triazol-l-yl)-2-(2,5-difluorophenyl)43utan-2-ol; and has the structural formula I:

Formula I

The ‘353 described the process for the preparation Isavuconazole, involve the use of 2-(2,5-difluoro-phenyl)-l-[l ,2,4]triazol-l-yl-butane-2,3-diol (referred herein after “diol base”) in an oil form, which is difficult to isolate and purify. The use of 2-(2,5-difluoro-phenyl)-l-[l ,2,4]triazol-l-yl-butane-2,3-diol base, without purification, reflects the purity of Isavuconazole and Isavuconazonium sulfate. However, the reported process not feasible industrially.

Thus, an object of the present invention is to provide simple, cost effective and industrially feasible processes for preparation of Isavuconazole or its salt thereof in enhanced yield as well as purity. In a particular present invention directs to novel stable polymorphs of Isavuconazole or its salt thereof.

Examples

Example-1: Preparation of Amorphous Isavuconazole

In a round bottomed flask charged ethanol (250 ml), thioamide compound (25.0 gm) and 4-cyano phenacyl bromide (18.4 gm) under stirring. The reaction mixture were heated to 70 °C. After completion of reaction the solvent was removed under vacuum distillation and water (250 ml) and Ethyl acetate (350 ml) were added to reaction mass. The reaction mixture was stirred and its pH was adjusted between 7 to 7.5 by 10 % solution of sodium bicarbonate. The layer aqueous layer was discarded and organic layer was washed with saturated sodium chloride solution (100 ml) and concentrated under vacuum to get residue. The residue was suspended in methyl tert-butyl ether (250 ml) and the reaction mixture was heated to at 40°C to make crystals uniform and finally reaction mass is cooled to room temperature filtered and washed with the methyl tert-butyl ether. The product was isolated dried to get pale yellowish solid product.

Yield: 26.5 gm

HPLC purity: 92.7%

Example-2: Preparation of crystalline Isavuconazole Base

Charged methylene dichloride (250 ml) and 25.0 gm Isavuconazole Hydrobromide compound of formula-II into 1.0 L flask and stirred. Added aqueous solution of sodium bi carbonate in to the reaction mass to obtained clear solution. The layers were separated and organic layer was washed with dilute hydrochloric acid solution followed by saturated solution of sodium chloride. Finally, Organic layer was concentrated under vacuum to get titled product.

Yield: 18.5 gm

HPLC Purity: 97%

Example-3: Preparation of crystalline Isavuconazole Hydrobromide

Charged isopropanol alcohol (250 ml) followed by thioamide compound (25.0 gm) and 4-cyano phenacyl bromide (18.4 gm) into 1.0 L flask. The reaction mixture was stirred and heated to 50 C, after completion of reaction the precipitated material was filtered and washed with isopropanol alcohol (25 ml). The wet cake is dried under vacuum for 4-5 hrs at 40 C to obtain off-white solid product.

Yield: 26.5 gm

HPLC Purity: 97.3%

Exaniple-4: Synthesis of 2-(2,5-difluoro-phenyl)-l -[l,2,4]triazol-l-yl-butane-2,3-diol oxalate

Dissolved crude 50 gm 2-(2,5-difluoro-phenyl)-l-[l ,2,4]triazol-l -yl-butane-2,3-diol base compound in 150 ml of ethyl acetate. Oxalic acid dihydrate 25 gm was added into the reaction mixture and stirred. Heat the reaction mixture for 1 hour at 50-55 °C. The reaction mixture was cooled to 25°C to 35°C. Toluene 300 ml was added into the reaction mixture to precipitate the solid. The precipitate was washed with toluene and dried under vacuum to obtain the solid crystalline form of titled compound.

Yield: 58 g

HPLC Purity: 76%

Exaniple-5: Synthesis of 2-(2,5-difluoro-phenyl)-l -[l,2,4]triazol-l-yl-butane-2,3-diol oxalate salt

Exemplified procedure in example 1 with the replacement ethyl acetate solvent with tetrahydrofuran and antisolvent toluene with petroleum ether were used to get the title compound.

Exaniple-6: Synthesis of 2-(2,5-difluoro-phenyl)-l -[l,2,4]triazol-l-yl-butane-2,3-diol oxalate

Exemplified procedure in example 1 with the replacement ethyl acetate solvent with isopropyl acetate and antisolvent toluene with diisopropyl ether were used to get the title compound.

Exaniple-7: Synthesis of 2-(2,5-difluoro-phenyl)-l -[l,2,4]triazol-l-yl-butane-2,3-diol oxalate

Exemplified procedure in example 1 wherein diethyl ether is used in place of ethyl acetate and toluene or heptane was used as antisolvent to get the title compound.

Example-8: Synthesis of 2-(2,5-difluoro-phenyl)-l -[l,2,4]triazol-l-yl-butane-2,3-diol oxalate

Exemplified procedure in example 1 wherein diethyl ether is used in place of ethyl acetate and isolation of the product were done by means of partial removal of the solvent under vacuum.

Example-9: Synthesis of 2-(2,5-difluoro-phenyl)-l -[l,2,4]triazol-l-yl-butane-2,3-diol oxalate

Exemplified procedure in example 1 wherein ethyl acetate is replaced with isopropyl acetate and further, the reaction mass was stirred at lower temperatures to about 10°C to about 15°C for 3-5 hours and subsequently precipitated product was isolated and dried.

Example-10: Synthesis of 2-(2,5-difluoro-phenyl)-l-[l ,2,4]triazol-l-yl-butane-2,3-diol base

Stirring the suspension of 260 ml water and 65 gm 2-(2,5-difluoro-phenyl)-l-[l,2,4] triazol-l-yl-butane-2,3-diol oxalate salt were added. The reaction mixture pH was adjusted by addition of 10 % aqueous sodium carbonate solution. The pH was maintained to about pH 7 to about 8, 300 ml dichloro methane was added into the reaction mixture with stirring. The layers were separated and dichloromethane layer was collected. Aqueous layer was extracted with 150 ml dichloromethane. Dichloromethane layer was combined and washed with water. Dichloromethane was distilled out to get titled compound.

Yield: 35 gm

Purity: 87%

Wockhardt Ltd chairman Habil Khorakiwala.

/////////NEW PATENT, WOCKHARDT LIMITED, WO 2016055918, ISAVUCONAZOLE