External ligand-free Pd-catalyzed 1,4-hydrosilylation of pyridines: mechanistic implication of dearomative remote hydride shift

Abstract

We report a simple, external ligand-free Pd catalytic system for the regioselective 1,4-hydrosilylation of pyridines and quinolines. The Pd catalyst exhibits broad substrate scope with excellent functional group tolerance, exclusively furnishing N-silyl-1,4-dihydropyridines and -quinolines. Mechanistic studies suggest a Pd(0)/(II) cycle involving dearomative intramolecular hydride shift, with product-releasing reductive elimination as the rate-determining step.