A series of of 6H-benzo[c]chromen-6-one derivatives were prepared via a Pd-catalyzed cross-coupling reaction of o-bromo benzoic acids and aryl formates using light-irradiation at room temperature. Preliminary studies on the reaction mechanism indicate pathways through esterification followed by C─H activation/cyclization.

Abstract

Dibenzopyranone is a privileged structure in natural products that exhibits multiple fascinating properties. Reported herein, is the synthesis of dibenzopyranone from o-bromo benzoic acids and aryl formates. The combination of a Pd-catalyst and light irradiation allows the reaction to proceed under mild conditions at room temperature. Preliminary mechanistic studies suggested that the reaction undergoes an esterification process followed by a cyclization to form the dibenzopyranone ring structure. This method provides a complementary approach for the synthesis of substituted benzo[c]chromen-6-one from readily available materials.