Unprecedented B–H Activation Through Pd‐Catalysed B–Cvinyl Bond Coupling on Borane Systems

A Pd‐induced cascade B–C vinyl coupling that produces multiple B–C vinyl bonds starting from a single B–I bond has been demonstrated. The process is most probably stimulated by the geometrical disposition of the B–H bonds confronting the B–Pd sites, along with the hydride character of the B–H units. Two and one B–C vinyl couplings on the metallacarborane substrate have been generally obtained, but formation up to six B–C vinyl bonds has been observed. A theoretical reaction mechanism involving an unprecedented B–H activation is proposed to interpret the multisubstitution process.