Total Synthesis of Tricolorin A via Interrupted Pummerer Reaction Mediated Glycosylation and One-pot Relay Glycosylation

Tricolorin A, a bioactive resin glycoside with a tetrasaccharide backbone and a 19-membered macrolactone, was synthesized stepwisely or in one-pot based on interrupted Pummerer reaction mediated (IPRm) glycosylation. The stepwise synthesis adopted a [2+2] assembly sequence, and all of the glycosidic bonds were constructed effciently by IPRm glycosylation employing paires of OPTB/OPSB and SPTB/SPSB glycosyl donors. The one-pot synthesis employed our recently developed one-pot relay glycosylation strategy, in which two different glycosidic bonds were sequentially constructed with only one equivalent of triflic anhydride. Both stratgegies assembled the tricolorin A with high efficiency, which demonstrated the great utilitarian potential of the IPRm glycosylation and one-pot relay glycosylation.