Glycosylation of 6 α,12 β-dihydroxy-20 R,25-epoxydammaran-3-one.

Glycosylation of 6 α,12 β-dihydroxy-20 R,25-epoxydammaran-3-one (panaxatriol 3-ketone, 2) under Koenigs-Knorr reaction conditions and the Helferich modification was studied. Condensation of 2 with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosylbromide ( 5) in the presence of AgO and 4-Å molecular sieves in CHCl gave acetylated 6 α,12 β-dihydroxy-20 R,25-epoxydammaran-3-one 12- O-β-D-glucopyranoside whereas in the presence of Hg(CN) in nitromethane at 25°C the tetrahydropyran ring opened and, depending on the ratio of reagents, acetylated 12-, 12,25-di-, or 6,12,25-tri -O-β-D-glucopyranosides of 6 α,12 β,25-trihydroxydammar-20(22) E-en-3-one formed. 6 α,12 β-Dihydroxy-20 R,25-epoxydammaran-3-one 12- O-β-D-glucopyranoside and 12-, 12,25-di-, and 6,12,25-tri- O-β-D-glucopyranosides of 6 α,12 β,25-trihydroxydammar-20(22) E-en-3-one were synthesized for the first time. [ABSTRACT FROM AUTHOR]