American Chemical Society
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A Boron–Boron Double Transborylation Strategy for the Synthesis of gem-Diborylalkanes

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posted on 2020-04-02, 12:35 authored by Jamie H. Docherty, Kieran Nicholson, Andrew P. Dominey, Stephen P. Thomas
Olefin hydroboration reactions provide efficient access to synthetically versatile and easily handled organoboronic esters. In this study, we demonstrate that the commercially available organoborane reagent 9-borabicyclo[3.3.1]­nonane (H-B-9-BBN) can serve as a catalyst for the sequential double hydroboration of alkynes using pinacolborane (HBpin). This strategy, which is effective for a wide range of terminal alkynes, is predicated upon a key C­(sp3)−B/B–H transborylation reaction. Transition-state thermodynamic parameters and 10-boron-isotopic labeling experiments are indicative of a σ-bond metathesis exchange pathway.