Process for preparing temozolomide

Abstract

The present invention provides a process for preparing highly pure Temozolomide base which includes recovery from the purification mother liquors by using an anionic exchange resin. By treating Temozolomide hydrochloride with a mixture of an organic acid, a water miscible organic solvent, and water, Temozolomide free base is obtained in an acidic medium. Due to the high sensitivity of Temozolomide to basic pH values the recovery-including process is especially advantageous because it enables obtaining high yields of highly pure Temozolomide base in acidic conditions. The process for producing Temozolomide base includes hydrolysis of the starting material 8-cyano-3-methyl-[3H]-imidazo[5,1-d]-tetrazin-4-one in acidic medium to obtain highly pure Temozolomide hydrochloride in high yield.

Dependencies are inferred from the claim text.