Rotenoid synthesis by Wadsworth–Emmons coupling and Mukaiyama cyclisation: application to 5-thiorotenoids

Abstract

A, new synthesis of general applicability to rotenoid structures is described, though its specific objectives were 5-thiorotenoids. The synthons carrying the A/B- and the B/C-ring components are coupled by Wadsworth–Emmons synthesis and the ring B chromene is formed by Mukaiyama directed aldol cyclisation: Michael addition completes the formation of the rotenoid at its correct oxidation state and in its stable cis-form. Examples with, and without 2,3-dimethoxylation in ring A are described.