B(C6F5)3-Catalyzed transfer 1,4-hydrostannylation of α,β-unsaturated carbonyls using iPr-tricarbastannatrane

Abstract

Tris(pentafluorophenyl)borane, B(C₆F₅)₃, has been found to be an effective catalyst to access the hydridoborate anion, [N(CH₂CH₂CH₂)₃Sn][HB(C₆F₅)₃], via hydride abstraction from the hypercoordinated tin reagent, iPr-tricarbastannatrane. This process has been applied to the B(C₆F₅)₃-catalyzed transfer 1,4-hydrostannylation of electron-deficient olefins, namely benzylidene barbituric acids. Insights into the mechanism have been obtained via a series of ¹H, ²H, ¹¹B, ¹³C, and ¹¹⁹Sn NMR spectroscopy, mass spectrometry, and labeling experiments.