Dibenzofuran and dibenzothiophene based palladium(ii)/NHC catalysts – synthesis and applications in C–C bond formation

Abstract

In the quest for a new ligand system for Pd(II)/NHCs, we developed new dibenzofuran and dibenzothiophene based palladium N-heterocyclic carbene catalysts D1–D6 in good yields. All the catalysts were characterized by multinuclear NMR spectroscopy and HRMS. The X-ray crystal structure of the representative dibenzothiophene based Pd(II)/NHC D4 was determined. Among the precatalysts, D1 was shown to be highly effective in the Suzuki–Miyaura cross-coupling reaction of heterocyclic bromides with boronic acids. Besides, D1 affords diverse arylated benzoxazoles via direct C–H bond functionalization with substituted bromo derivatives.