Hydroboration without a B–H bond: reactions of the borinium cation [(iPr2N)2B]+ with alkyne, nitrile, ketone and diazomethane

Abstract

The borinium cation [(iPr₂N)₂B]⁺ (1⁺) is shown to react with PhCCH, PhCN, Ph₂CO, and Ph₂CN₂ to effect a net hydroboration, affording borenium complexes of the form [(iPr₂N)B(iPrNCMe₂)(L)][B(C₆F₅)₄] (L = CHCHPh 2, NCHPh 3, OCHPh₂4, NHNCPh₂5). The nature and reaction of 1⁺ with PhCCH was probed computationally and the reduction of these unsaturates is shown to occur via hydride transfer from an isopropyl group to the alkyne, thus effecting hydroboration without a B–H bond.