Reductive S N 2' Reaction of Epoxydienoate with Borane and its Application to the Synthesis and Structural Revision of an Antitumor Active Torrubiellutin Analogue.

A reductive S N 2' reaction of epoxydienoates and epoxyenoates with borane was developed to afford skipped dienoates and unconjugated enoates with trisubstituted Z-alkene linked to asymmetric centers on one side or both sides. This reaction was successfully applied to the alternative synthesis of an antitumor active artificial analogue of torrubiellutin C. A geometric isomer for α,β-unsaturated amide of the artificial analogue was also synthesized. These syntheses clarified the true structure of the antitumor active artificial analogue of torrubiellutin C.