According to the longstanding definition, a frustrated Lewis pair (FLP) is the combination of a Lewis acid and a Lewis base that do not quench each other because of steric hindrance and/or geometric constraints. Since 2011, in an effort to broaden the scope of FLPs, our research group has been interested in using classical Lewis pairs that are synthetically available to effect FLP transformations. The geometrically constrained ortho-phenylene bridged amino-hydroboranes proved to be particularly interesting and active catalysts, notably for the borylation of Csp2-H and S-H bonds. Moreover, a recent mechanistic study proved that despite existing as stable Lewis adducts in their ground state, less bulky analogues are more active catalysts for the Csp2-H borylation, suggesting that the presence or absence of Lewis adducts does not always correlate to the FLP activity. Finally, while studying this reactive FLP framework, we also discovered interesting rearrangements, notably leading to the formation of a diborane and the first example of a Csp3-H activation by a FLP. The synthesis and characterization of these new species, as well as the experimental and computational investigation of their reactivity, will be presented.

Synthesis and reactivity of amino-hydroborane frustrated Lewis pairs

256th National Meeting (2018)

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