Visible-Light-Induced Regioselective Functionalization of α-Olefin: Development of One-Pot Photo-Synthesis of C 3 -Substituted Dihydrobenzofurans.

A method for the catalytic regioselective synthesis of C 3 -substituted dihydrobenzofurans (DHBs) via [2 + 2] photocycloaddition of alkene and p -benzoquinone is developed. This method realizes the rapid synthesis of DHBs with readily available substrates and simple reaction conditions by using Lewis acid B(C 6 F 5 ) 3 and Lewis base P( o -tol) 3 as a catalyst in combination with the classical Paternò-Büchi reaction.