Iridium/palladium dual photocatalysis for oxidative decarboxylative esterification of alcohols using α-keto acids

Abstract

Herein, we report an unprecedented oxidative decarboxylative C–O cross-coupling reaction for the esterification of feedstock α-keto carboxylic acids and alcohols under mild conditions. This metallaphotocatalytic approach relies upon in situ acyl radical formation and its cross-coupling with alcohols through O–H bond activated Pd(II) species. This decarboxylative dehydrogenation route allows an immense scope for the conversion of electronically diverse, fused benzene and heterocyclic aromatic and aliphatic alcohols with natural and pharmaceutical architectures to their corresponding benzoate analogs. In contrast to traditional approaches, the present method also overcomes the regio-specific esterification of N-heterocyclic alcohols at their 3-position over their respective 2 and 4 positions. Moreover, complementary density functional theory (DFT) based investigations have been employed to unearth Single Electron Transfer (SET) based reductive mechanistic avenues, which are accessed in such unique photocatalytic conversions.