Semisynthetic analogues of ginsenosides, glycosides from ginseng

Abstract

Glycosylation of the dammar-24-ene-3,12β,20(S)-triols with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide (A) in the presence of silver oxide in dichloro-methane gives a mixture of the acetylated 3-, 12-, 20-, 3,12-di-, and 3,20-di-O-β-d-glucopyranosyl derivatives in a total yield of 83-84.5%. Under similar conditions, the 3-O-acetyl derivatives of dammar-24-ene-3,12β,20(S)-triols give a mixture of 12- and 20-O-β-d-glucopyranosyl derivatives. Condensation of betulafolienetriol [dammar-24-ene-3α,12β,20(S)-triol] both with the glycosyl bromide A in the presence of mercuric cyanide in nitromethane and with 3,4,6-tri-O-acetyl-β-d-glucopyranose 1,2-(tert-butyl orthoacetate) in the presence of 2,4,6-trimethyl-pyridinium perchlorate in chlorobenzene under azeotropic distillation results in dehydration and 20-dehydroxyglucosides are formed. © 1988.