Proton‐Coupled Electron Transfer Processes in the Decarboxylative 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 reductive photocatalytic conditions. Herein, we present a method that allows the introduction of primary alkyl radicals prepared through the oxidative‐PCET ring opening of cycloalkanols under very mild reaction conditions. The method presents a broad scope and can be carried out on a large scale under photo‐flow conditions. Moreover, mechanistic investigations allow the corroboration of decarboxylation under polar conditions.