A lutidine-bridged bis-perimidinium salt: Synthesis and application as a precursor in palladium-catalyzed cross-coupling reactions

Abstract

A novel lutidine-bridged bis-perimidini-um dibromide 3 was synthesized in quantitative yield from cheap commercial starting materials. The bisylidene prepared therefrom in situ upon deproto-nation is a potent precatalyst in palladium-catalyzed Heck and Suzuki cross-coupling reactions under aerobic conditions, and is efficient even with a ppm scale catalyst loading. Its stronger o-donor character is held to be responsible for its superior catalytic performance compared with imidazole- and benz-imidazole-based analogues bearing the same skeleton precursors. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.