Organosilicon compounds anionic species

Since the preparation of anionic species or organosilicon compounds is largely restricted by its reaction conditions, the synthetic utility of silyl anions for the synthesis of organosilicon compounds is limited. However silyllithiums possessing one or more phenyl groups on a silicon atom are readily prepared by the reductive metallation of the corresponding halosilanes with lithium. Allylsilanes are synthesized by the reaction of allyl acetates with the cuprate prepared from such a reagent (eq (47)) [43]. 

Theoretical aspects of organosilicon compounds D. Anionic Species... 

The reaction is a sequential Michael addition of an organosilicon compound to a,P-unsaturated esters, ketones, rritriles, and carboxamides. Chain propagation proceeds by transfer of the silyl group from the silyl ketene acetal catalyst to the monomer with the generation of a new ketene acetal, and if inadvertent termirration is avoided, repeated addition of the monomer leads to a living polymer. The typical reaction shown as follows rrses the catalyst l-methoxy-l-trimethylsiloxy-2-methyl prop-l-ene, but a cocatalyst is required, and this is either an anionic species or a Lewis acid. 

Alternatively, unreactive mixtures of organosilicon hydrides and carbonyl compounds react by hydride transfer from the silicon center to the carbon center when certain nucleophilic species with a high affinity for silicon are added to the mixture.76 94 This outcome likely results from the formation of valence-expanded, pentacoordinate hydrosilanide anion reaction intermediates that have stronger hydride-donating capabilities than their tetravalent precursors (Eq. 6).22,95 101... 

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