Phosphinoboration

04 January 2015 - Organic chemistry

phosphinoborination  In a recent report (DOI) Daley et al. express surprise that of the many bonds containing boron that have been used in the exploration of addition reactions, for example the B-H bond in hydroboration, the boron - phosphorous bond is not one of them. Triggered by a 2013 report by Breuning (DOI), the first on this topic, Daley ventured further.

A compound containing a P-B bond was constructed from diphenylphosphine and 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane. This compound was found to react in 1,2-addition with aldehydes without the need of a catalyst. Other substrates uncovered were allenes and terminal alkynes (though requiring a catalyst).

It is a bit curious that this type of new chemistry appears well after the introduction of frustrated Lewis pairs that also deals with P/B chemistry in a comparable way.