Pd-Catalyzed Dual-γ-1,1-C(sp3)–H Activation of Free Aliphatic Acids with Allyl–O Moieties

Abstract

Allyl alcohols represent a unique class of coupling partners in C–H functionalization reactions. In this work, we report a simple strategy that involves dual-1,1-C(sp3)–H activation of free aliphatic acids, leading to the direct synthesis of γ-lactones that contain α,β-unsaturated groups at the γ-position. Various allyl alcohols including primary, secondary, tertiary, etc., have been used as suitable coupling partners to generate a diverse range of γ-lactones. A number of aliphatic acids including the long-chain ones have been used as substrates in the protocol. A mechanistic investigation has been carried out and suggests C–H activation to be the rate-determining step and a subsequent allylic C–H activation in the reaction. The synthesized lactones having α,β-unsaturated fragments attached are expected to be useful in the synthesis of complex molecules via further synthetic manipulation.