AN IMPROVED PROCESS FOR THE PREPARATION OF 5,6 -DIHYDRO -4H-4(S)-ETHYLAMINO-6(S)-METHYLTHIENO2,3-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 usingdibenzoyl -L- tartaric acid monohydrate or di-p-toluoyl-L-tarrtaric acidmonohydrate as a chiral resolving agent in presence of methanol to obtainhemitartarate salt, purifying it to obtain hemitartarate salt of 5,6-dihydro-4H-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 of0.1 % and further converting into its pharmaceutically acceptable salts,preferably hydrochloride salt.