| 摘要 |
PURPOSE: To obtain ginsenoside Rh2 useful as raw material for a medicine such as a carcinostatic agent and a perfume by oxidizing a specific terpene with a carbonyl compound, acetylating, reducing, reacting the resultant substance with a halogenated saccharide and further treating an alkali metal alkoxide. CONSTITUTION: A terpene of formula I (A is 3α-OH or 3β-OH) is oxidized with a carbonyl compound of the formula R2 COR3 (R2 and R3 are each a 2-10C alkyl or alkylaryl) in the presence of an Al trialklxide of the formula Al(OR1 )3 (R1 is a 1-10C alkyl) to give 3-keto-betulafolienetriol. Then 3-keto- betulafolienetriol is acetylated, reduced to give 12-acetyl-protopanaxadiol, which is reacted with an α-glucopyranosyl halide tetraalkylate, treated with an alkali metal alkoxide in an alcohol and a protecting group is removed to give the objective ginsenoside Rh2 of formula III. |
