| Abstract
| - Two trisaccharide steroidal saponins, dioscin (1)and Xiebai saponin I (2) with various bioactivities, were efficiently synthesized using the newly developed glycosyl N-phenyl trifluoroacetimidates (10−13) as glycosylation donors. Thus, dioscin was synthesized in five steps and a 33%overall yield from diosgenin and glycosyl trifluoroacetimidates (10 and 11). Xiebai saponin I was synthesized in eightsteps and a 32% overall yield from laxogenin and glycosyltrifluoroacetimidates (10, 12, and 13), whereupon, the raresteroid laxogenin was prepared from diosgenin in four stepsand an overall 69% yield. All the glycosylation reactionsinvolved in the present syntheses demonstrated that glycosyltrifluoroacetimidates were successful donors comparable tothe corresponding glycosyl trichloroacetimidates.
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