Ligand-Enabled PdII -Catalyzed Iterative γ-C(sp3)-H Arylation of Free Aliphatic Acid

Abstract

C-H functionalization of aliphatic carboxylic acids without attaching exogenous auxiliary has been so far limited at the proximal β-position. In this work, we demonstrate a ligand enabled palladium catalyzed first regioselective distal γ-C(sp3)-H functionalization of aliphatic carboxylic acids without incorporating an exogenous directing group. Aryl iodides containing versatile functional groups including complex organic molecules are well tolerated with good to excellent yields during the γ-C(sp3)-H arylation reaction. Interestingly, weak coordination of carboxylate group can be further extended for sequential hetero di-arylation. Application of the protocol has been showcased by synthesizing substituted α-tetralone. Mechanistic investigations have been carried out to shed light on the reaction pathway.

Keywords: iterative arylation; mechanistic studies; natural product incorporation; α-tetralone synthesis; γ-arylation.