Visible-light-mediated cascade difunctionalization/cyclization of alkynoates with acyl chlorides for synthesis of 3-acylcoumarins

A new visible-light-mediated radical cyclization of alkynoates with acyl chlorides is described for the one-pot construction of diverse 3-acylcoumarins with high efficiency and selectivity. This method is successful by sequential difunctionalization of an alkynes C-C triple bond with the C-Cl bonds of acyl chloride and aromatic C(sp(2))-H bonds. The cyclization is proposed to simultaneously form two new carbon-carbon bonds, and involves radical acylation, 5-exo-trig cyclization, and ester migration. (C) 2018 Elsevier Ltd. All rights reserved.