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

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. A photocascade strategy is disclosed for the synthesis of trans -dihydrofurocoumarin utilising the EDA complex followed by 1,4-radical conjugate addition of pyridinium ylide.