Silylmercury compounds, transmetalation

Transmetalation of silylmercury compounds with lithium (equation 3) ... 

The silylmercury compounds are most conveniently available by reacting a chlorosilane with sodium amalgam. In contrast to the two methods mentioned above, which in most cases require polar, aprotic solvents such as THF, DME or HMPA, transmetalation reactions can be performed in nonpolar solvents and often result in better yields than when performed in ethereal solvents. 

Transmetallation of silylmercury compounds, which are most easily available via the reaction of a silane with (/-Bu)2llg, appears to be the most convenient method for the preparation of cyclic potassium oligosilyl compounds c-(MegSis)K (19)83c as well as c-(MenSi6)K (20)84 were obtained by Hengge and coworkers from the corresponding mercury compound by means of a Na/K alloy in THF (equation 33). 

A disadvantage of both methods is that the obtained silylanions are usually adducts of the donor solvents used for their synthesis. These donor molecules can sometimes cause problems in subsequent reactions. Base-free silylanions can be obtained by means of transmetalation from silylmercury compounds (eq. In this case, hydrocarbon solvents can be used to generate the... 

Silyllithium compounds may also be prepared by the transmetalation reaction between silylmercury and Li. The requisite silylmercury may be prepared from the corresponding chlorosilane or hydrosilane. The latter can be applied to the synthesis of polysilanyllithium. Equation (17) is an example. ... 

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