Nucleophilic Displacement at Silicon Controlling Factors of the Stereochemistry

NUCLEOPHILIC DISPLACEMENT AT SILICON CONTROLLING FACTORS OF THE STEREOCHEMISTRY 

Displacement reactions must proceed either with retention or inversion of configuration at silicon. The change in stereochemistry is mainly a function of the nature of the leaving group and of the electronic character of the nucleophile. 

As outlined in our previous review (5), coupling reactions of a nucleophilic reagent Nu with an organosilane RaSi—X occur only by a one-stage nucleophilic mechanism [Eq. (1)]. The halosilanes are not prone to one-electron transfer which could lead to a two-stage mechanism [Eq. (2)]. 

In the following sections we shall examine the factors controlling the stereochemistry of substitution at silicon. 

As shown in Table I, for nucleophiles of diverse nature, the stereochemical outcome depends strongly upon the nature of the leaving group. The following comments can be made  

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