Electron donor–acceptor complex enabled photocascade strategy for the synthesis of trans-dihydrofuro[3,2-c]chromen-4-one scaffolds via radical conjugate addition of pyridinium ylide

Abstract

A visible-light-induced photocascade strategy is disclosed for the synthesis of trans-dihydrofuro[3,2-c]chromen-4-one scaffolds. The photocascade consists of electron donor–acceptor (EDA) complex enabled formation of arylidene coumarinone, followed by 1,4-radical conjugate addition (1,4-RCA) of an in situ generated pyridinium ylide radical (PyYR) towards diastereoselective formation of the trans-dihydrofuro[3,2-c]chromen-4-one scaffold in good to excellent yield. Thorough mechanistic investigations comprising photophysical, spectroscopic, electrochemical and DFT studies provide further insights into the reaction mechanism.