AN IMPROVED PROCESS FOR THE PREPARATION OF 5,6 -DIHYDRO -4H-4(S)-ETHYLAMINO-6(S)-METHYLTHIENO[2,3-b] THIOPYRAN-2-SULFONAMIDE- 7,7 -DIOXIDE AND ITS SALT

摘要

The present invention relates to resolution of (cis, trans) 5,6 -dihydro -4H-4-ethylamino-6-methylthieno[2,3-b] thiopyran-2-sulfonamide-7,7 -dioxide using dibenzoyl -L- tartaric acid monohydrate or di-p-toluoyl-L-tarrtaric acid monohydrate as a chiral resolving agent in presence of methanol to obtain hemitartarate salt, purifying it to obtain hemitartarate salt of 5,6-dihydro-4 H-4 (S) -ethyl amino-6(S) methylthieno [2,3-b] thiopyran-2-sulfonamide - 7,7 -dioxide with de of >99% , Chemical purity >99.5% with cis isomer content of <0.1 % and further converting into its pharmaceutically acceptable salts, preferably hydrochloride salt.