Visible Light Induced 6π Electrocyclization: Divergent Synthesis of Seven Membered Ring Derivatives

Abstract

We reported the first visible light-induced 6π electrocyclic reaction for the divergent synthesis of seven-membered ring derivatives. When BHT was employed, the indole skeletons bearing seven-membered rings underwent a 6π/4π cyclization to form [7-4-5] tricyclic systems fused with indoles. In contrast, the use of TBAI enabled the conversion of the same starting materials into [7-7] bicyclic scaffolds tethered with indoles via an electron donor-acceptor (EDA) complex. Notably, this reaction has significant advantages such as high atom economy and carbon efficiency, as well as the absence of external photocatalysts.