1,1-Phosphaboration of CC and CC bonds at gold

Abstract

The phosphine-borane iPr₂P(o-C₆H₄)BFXyl₂ (Fxyl = 3,5-(F₃C)₂C₆H₃) was found to react with gold(I) alkynyl and vinyl complexes via an original 1,1-phosphaboration process. Zwitterionic complexes resulting from Au to B transmetallation have been authenticated as key intermediates. X-ray diffraction analyses show that the alkynyl–borate moiety remains pendant while the vinyl-borate is side-on coordinated to gold. According to DFT calculations, the phosphaboration then proceeds in a trans stepwise manner via decoordination of the phosphine, followed by anti nucleophilic attack to the π-CC bond activated by gold. The boron center acts as a relay and tether for the organic group.