Photosensitizer-free, visible light-mediated recyclable gold-catalyzed cross-coupling of aryldiazonium salts and alkynyltrimethylsilanes

Abstract

A new mesoporous SBA-15-anchored triphenylphosphine–gold(I) complex [SBA-15-Ph₃PauNTf₂] was synthesized via the condensation of (4-(chloromethyl)phenethyl)trimethoxysilane with SBA-15, followed by reaction with (2-(diphenylphosphino)phenyl)methanol and Me₂SAuCl and then treatment with AgNTf₂ and characterized by different physico-chemical techniques. In the presence of 10 mol% of SBA-15-Ph₃PAuNTf₂, the photosensitizer-free cross-coupling reaction of aryldiazonium tetrafluoroborates and alkynyltrimethylsilanes proceeded smoothly in acetonitrile under irradiation with blue LEDs at room temperature to afford diverse arylalkynes in moderate to good yields with high functional group tolerance, including aryl halides incompatible with traditional cross-coupling. This new heterogenized gold(I) catalyst could be easily recovered through a simple centrifugation process and reused at least nine times without any significant drop in its catalytic efficiency.