15 - Synthesis of Organoboron, Organosilicon and Organophosphorus Compounds from Organomagnesium Compounds

Abstract

This chapter discusses the synthesis of organoboron, organosilicon and organophosphorus compounds from organomagnesium compounds. Although alternative methods for preparing organoboron compounds are available, reactions of organomagnesium compounds with boron halides, borate esters, and so on, remain useful, particularly for arylboron compounds and for compounds with mixed ligands. Much of the early work on the synthesis of organosilicon compounds was based on reactions between Grignard reagents and silicon halides, to a lesser extent on silicate esters, and much effort was devoted to optimizing stepwise reactions. Although these reactions have been largely superseded for the industrial production of simple alkylsilyl halides as precursors to silicones, they—with the analogous organolithium methods—remain the principal primary laboratory route to organosilicon compounds. A useful alternative to reactions of preformed Grignard reagents is a “Barbier” procedure in which an organic halide, magnesium and a silicon halide react together. In some cases the organomagnesium compound may be an intermediate, and the technique has been particularly employed when the Grignard reagent becomes unstable. Reactions of organomagnesium compounds with phosphorus(Ill) halides and trialkyl phosphites are normally easy and straightforward.