Catalyst-Controlled Site-Selective Acylation and its Application to Unconventional Total Synthesis of Natural Glycosides

We have developed a method for catalytic site-selective acylation of various glucose derivatives, which enables to deliver acyl groups at the secondary C(4)-OH in the presence of the free primary C(6)-0H. Under these catalyst-controlled conditions, the reaction takes place with reversal of the intrinsic reactivity. Based on this protocol, unconventional retrosynthetic analysis for total synthesis of natural glycosides was proposed: (1) final-stage site-selective introduction of a p-oumaroyl group into the unprotected natural glycoside precursors for total synthesis of multifidosides A-C, (2) site-selective and sequential introduction of galloyl groups into unprotected glucose for extremely short step total synthesis of ellagitannins.