Studies directed toward the synthesis of reiswigin A: Total synthesis of (±)-epi-reiswigin A

Abstract

As a testing ground for the practical application of asymmetric synthesis, (–)-reiswigin A, a potent antiviral agent, was chosen as a target for total synthesis. Initial studies were undertaken to prove the viability of the key asymmetric step, enantioselective deprotonation of an intermediate meso-bicyclic ketone, using a chiral lithium amide base. Enantiomeric excesses in the range of 90%–94% were routinely obtained, even on runs as large as 10 g. Unfortunately, conversion of this key enantio-enriched intermediate to the natural product proved unsuccessful. While these studies were enroute, a parallel synthesis using the racemic compound was transformed into (±)-epi-reiswigin A.Key words: asymmetric deprotonation, synthesis, (±)-epi-reiswigin A.