SIMPLIFIED PREPARATION OF THE GINSENOSIDE-RH-2 MINOR SAPONIN FROM GINSENG

摘要

Condensation of the 12-O-acetylderivative of 20(S)-protopanaxadiol [dammar-24-ene-3 beta,12 beta,20(S)-triol] with tetra-O-acetyl-alpha-D-glucopyranosyl bromide in the presence of silver oxide in dichloroethane, followed by deprotection with sodium methoxide in methanol, results in formation of the 3-O-beta-D-glucopyranosyldammar-24-ene-3 beta,12 beta,20(S)-triol identical with natural ginsenoside-Rh-2. The 12-O-acetyl-20(S)-protopanaxadiol is easily prepared from betulafolienetriol via the 3-keto-12-O-acetylderivative followed by NaBH4 reduction. This comparatively simple five-step synthesis makes this hitherto rare ginsenoside relatively accessible. (C) 1997 Elsevier Science Ltd. [References: 6]