Photoinduced Formal [4+2] Cycloaddition of Two Electron-deficient Olefins: Synthesis of Lucidumone

Abstract

Electronically mismatched Diels−Alder reaction between two electron-deficient components is synthetically useful and yet underdeveloped under thermal conditions. Herein, a photoinduced formal [4+2] cycloaddition of enone with a variety of electron-deficient dienes is described. Key to the success of this stepwise methodology relies on a C−C bond cleavage/rearrangement of the cyclobutane based overbred intermediate via diversified mechanistic pathways. Based on this annulation method, total synthesis of lucidumone is achieved in five steps.