A Rh(iii)-catalyzed cascade C–H functionalization/cyclization reaction of salicylaldehydes with diazomalonates for the synthesis of 4-hydroxycoumarin derivatives

Abstract

A cascade C–H functionalization/cyclization reaction of salicylaldehydes with α-diazomalonates has been developed for the synthesis of 4-hydroxycoumarin derivatives under the catalysis of rhodium(III) and in the presence of acetic acid. A plausible mechanism involving aldehydic C(sp²)–H activation by rhodium(III) and rhodium(III) catalyzed carbene insertion is also proposed.