Electron transfer promoted photochemical reductive radical cyclization reactions of allyl 2-bromoaryl ethers

Tin-free, photoinduced electron transfer promoted reductive radical cyclization reactions of allyl 2-bromoaryl ethers in the presence of NaOH in 2-PrOH were found to take place efficiently to give 3-methyl-2,3-dihydrobenzofurans. In contrast to conventional radical cyclization reactions that employ AIBN/Bu3SnH in benzene, the new method utilizes NaOH and 2-PrOH that are both readily available and benign. Consequently, the newly developed photochemical process serves as a versatile and environmentally friendly method for carrying out aryl radical cyclization reactions.