Abstract
The bond activation chemistry of B(C6F5)3 and related electron-deficient boranes is currently experiencing a renaissance due to the fascinating development of frustrated Lewis pairs (FLPs). B(C6F5)3's ability to catalytically activate Si-H bonds through η(1) coordination opened the door to several unique reduction processes. The ground-breaking finding that the same family of fully or partially fluorinated boron Lewis acids allows for the related H-H bond activation, either alone or as a component of an FLP, brought considerable momentum into the area of transition-metal-free hydrogenation and, likewise, hydrosilylation. This review comprehensively summarises synthetic methods involving borane-catalysed Si-H and H-H bond activation. Systems corresponding to an FLP-type situation are not covered. Aside from the broad manifold of C=X bond reductions and C=X/C-X defunctionalisations, dehydrogenative (oxidative) Si-H couplings are also included.
Highlights
The ground-breaking finding that the same family of fully or partially fluorinated boron Lewis acids allows for the related H–H bond activation, either alone or as a component of an frustrated Lewis pairs (FLPs), brought considerable momentum into the area of transition-metal-free hydrogenation and, likewise, hydrosilylation
This review comprehensively summarises synthetic methods involving boranecatalysed Si–H and H–H bond activation
The potent boron Lewis acid tris(pentafluorophenyl)borane [B(C6F5)[3], Fig. 1] is one of those molecules that revealed its relevance to synthetic chemistry long after its discovery
Summary
Obvious use, these reports laid dormant for decades with hardly any citations. The situation changed in the early 1990s when. Marks and co-workers found that B(C6F5)[3] and cognate electrondeficient boranes are excellent co-catalysts in metallocenemediated alkene polymerization.[2] B(C6F5)3’s ability to act as catalyst in its own right was discovered by Piers and co-workers in the late 1990s These authors showed that B(C6F5)[3] catalyses CQX bond hydrosilylations[3] (reduction) as well as dehydrogenative Si–O couplings[4] (oxidation) by a counterintuitive mechanism. Julia Hermeke (born in 1986 in Neuruppin/Germany) studied chemistry at the Freie Universitat Berlin (2006–2009) and at the University of Hong Kong (2009–2011). She spent internships with Bayer Schering Pharma. Type systems as these were comprehensively covered by several reviews in recent years.[9,10]
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