Frustrated Lewis Pair Chemistry: Searching for New Reactions

Abstract

Frustrated Lewis pair chemistry has taken a steep development in the recent years. It offers possibilities of developing new variants of known reactions and of finding new chemical transformations. This is demonstrated and described by the recently developed FLP-formylborane chemistry, which has led to the formation of the unique (η² -formylborane)FLP adducts and opened a way of preparing a genuine formylborane compound, which shows an interesting follow-up chemistry. FLPs have helped finding phosphorus analogues of the enamine Stork reaction and the Claisen reaction. These reactions lead to new organophosphorus compounds and they make new phosphane/borane systems available. P/B FLPs add to a variety of small main group element oxides. They undergo 1,2-addition reactions to CO₂ , SO₂ and other heterocumulenes and they feature unique 1,1-addition reactions to carbon monoxide, to isonitriles and even to nitric oxide (NO), the latter yielding examples of a new class of persistent nitroxide radicals, the FLPNO nitroxyls. Eventually, some remarkable radical reactions of FLPs and related compounds are briefly mentioned.

Keywords: activation; boron; frustrated Lewis pairs; nitrogen; phosphorus.