Photoorganocatalytic synthesis of lactones via a selective C-H activation-alkylation of alcohols

Selective C-H activation is an area of growing importance in modern organic chemistry. Herein, we report our efforts in combining organocatalysis and photocatalysis for the development of a highly efficient and selective visible-light mediated protocol for the C-H activation and addition of various alcohols to a plethora of Michael acceptors, followed by a cyclization reaction leading to lactones, a repeatedly occurring motif in nature. Utilizing phenylglyoxylic acid as the photocatalyst and common household bulbs as the light source, we describe a versatile alpha-alkylation/lactonization of alcohols witha alpha,beta-unsaturated esters leading to products in excellent yields. The reaction mechanism was extensively studied.