Sonogashira Cross-Coupling of Aryltrimethylammonium Salts

A protocol for C(sp)-C(sp(2)) bond formation via the Sonogashira coupling reaction involving C-N bond cleavage with aryltrimethylammonium triflate as an electrophilic coupling partner is described in this work. The reactions proceeded well under mild conditions with a stoichiometric ratio of alkyl, aryl, or heteroaryl acetylenes and provided yields of up to 93%. Numerous useful functional groups were tolerated under the reaction conditions. Direct amine alkynylation can be achieved through a onepot process without the isolation of ammonium salt. The protocol can be performed on a gram scale. Density functional theory calculations were performed to investigate the reaction mechanism that involved oxidative addition, alkyne coordination, deprotonation, and reductive elimination, which yielded the cross-coupling product.