Proton-Coupled Electron Transfer Processes in the Decarboxy-lative Synthesis of C-4 Substituted Chroman-2-ones

Chroman-2-one derivatives are biologically relevant structures that present interesting pharmacological and biological properties, being the C-4 alkylated derivatives of particular interest. The methods described in the literature allow the C-4 functionalization of coumarins with secondary and tertiary alkyl radicals, as well as aryl radicals produced under reduc-tive photocatalytic conditions. Herein, we present a method that allows the introduction of primary alkyl radicals pre-pared through the oxidative-PCET ring opening of cycloalkanols under very mild reaction conditions. The method pre-sents a broad scope and can be carried out on a large scale under photo-flow conditions. Moreover, mechanistic investiga-tions allow the corroboration of de decarboxylation under polar conditions.