Catalytic stereoselective synthesis of β-digitoxosides: Direct synthesis of digitoxin and C1'-epi-digitoxin

摘要

A mild and atom-economic rhenium(V)-catalyzed stereoselective synthesis of β-d-digitoxosides from 6-deoxy-d-allals has been described. This β-selective glycosylation was achieved probably because of the formation of corresponding α-digitoxosides disfavored by 1,3-diaxial interaction. In addition, this method has been successfully applied to the synthesis of digitoxin trisaccharide glycal for the direct synthesis of digitoxin and C1'-epi-digitoxin.