Process for large scale production of 1-isopropyl-3--1h-indazole oxalate

A process for large scale production of 1-Isopropyl-3-{5-[1-(3-methoxypropyl)piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole oxalate of formula (I),

• the process comprising the steps of:
• Step (i):
• coupling of 1-(3-Methoxypropyl) piperidine-4-carboxylic acid hydrazide of formula 1 with 1-Isopropyl-1H-indazole-3-carbonyl chloride of formula 2
• in presence of dichloroethane at a temperature in the range of 20° C. to 35° C. for a period of 1.5 hours to 2.5 hours to obtain N-[1-(3-Methoxypropyl) piperidine-4-carbonyl] N′-(1-isopropyl-1H-indazole-3-carbonyl) hydrazine of formula 3;
• Step (ii):
• cyclizing N-[1-(3-Methoxypropyl) piperidine-4-carbonyl] N′-(1-isopropyl-1H-indazole-3-carbonyl) hydrazine of formula 3 in presence of thionyl chloride in solvent selected from dichloromethane, 1,2-dichloroethane and chlorobenzene at a temperature in the range of 60° C. to 95° C. for a period of 8 hours to 10 hours to obtain 1-isopropyl-3-{5-[1-(3-methoxypropyl) piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole of formula 4;
• Step (iii):
• purifying 1-isopropyl-3-{5-[1-(3-methoxypropyl) piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole of formula 4 using mixture of acetic acid and water at a temperature in the range of 20° C. to 35° C.;
• Step (iv):
• reacting 1-isopropyl-3-{5-[1-(3-methoxypropyl) piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole of formula 4 with oxalic acid in presence of isopropanol at a temperature in the range of 20° C. to 35° C. for a period of 1 hour to 4 hours to obtain 1-Isopropyl-3-{5-[1-(3-methoxypropyl) piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole oxalate of formula (I);
• Step (v):
• recrystallizing compound of formula (I) using a mixture of isopropanol and water at a temperature range of 70° C. to 80° C. for a period of 15 hours to 17 hours.