Pd(ii) auxiliary assembling and diverse transformations via inert C(sp3)–H bond activation

Abstract

The construction of new C–C bonds via inert C(sp³)–H bond activation has garnered significant achievements in recent decades, particularly with palladacycles serving as pivotal intermediates. However, a thorough investigation into the synthesis of isolable palladacycles and their diverse transformations through this strategy remains largely unexplored. Herein, we present a facile and practical protocol for the assembly of a diverse array of Pd(II) auxiliaries from cyclopropenes and aliphatic amides with the formation of a new C–C bond via inert C(sp³)–H bond activation. The resulting palladium complexes enable efficient access to a wide range of aliphatic/unsaturated acids, amides, lactones, and lactams. A plausible reaction mechanism was proposed involving a cascade of C–H bond activation, carbene migration, and C–C bond formation processes, supported by comprehensive control experiments, kinetic isotope effect (KIE) studies, and density functional theory (DFT) calculations.