Phosphine–Borane Ligands Induce Chemoselective Activation and Catalytic Coupling of Acyl Chlorides at Palladium

Acyl
chlorides are highly reactive and widely used substrates in
catalytic cross-coupling reactions, but so far, site selectivity over
other functional groups has remained an issue. In this work, Pd complexes
deriving from the phosphine–boranes [i-Pr2P­(o-C6H4)]2BFXyl and i-Pr2P­(o-C6H4)­BFXyl2 (Fxyl = 3,5-(F3C)2C6H3) were found to preferentially
activate acyl chlorides over C–I, C–Br, C–Cl,
C–OTf, and C–OTs bonds. The system is amenable to catalysis
(Stille and Negishi couplings), providing a simple and efficient means
to forge C­(O)–C bonds in a site-selective manner and
to readily access functionalized ketones. To gain insight into the
role and influence of the ambiphilic ligands, key Pd complexes have
been authenticated and the reaction profiles have been analyzed by
density functional theory (DFT) calculations.