Glycosylation of triterpenoids of the dammarane series. X. Regio- and stereoselective synthesis of 20(S)-protopanaxadiol 3-O-β-D-glucopyranoside (ginsenoside Rh2)
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The regio- and stereoselective synthesis of ginsenoside Rh2, which possesses antitumoral activity, has been effected by the glycosylation of 12β-acetoxydammar-24-ene-3β,20(S)-diol. Condensation with α-acetobromoglucose was carried out in the presence of silver oxide in dichloroethane at room temperature, and the yield of the desired glycoside amounted to 50%. A method for the selective protection of the C-12-OH group of dammar-24-ene-3β,12β,20(S)-triol [20(S)-protopanaxadiol] has been proposed.
KeywordsGinsenoside Silver Oxide Triol Stereoselective Synthesis Sodium Tetrahydroborate
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