Exchange reactions organolithium compounds

This type of metallic exchange is used much less often than 12-32 and 12-33. It is an equilibrium reaction and is useful only if the equilibrium lies in the desired direction. Usually the goal is to prepare a lithium compound that is not prepared easily in other ways, for example, a vinylic or an allylic lithium, most commonly from an organotin substrate. Examples are the preparation of vinyllithium from phenyl-lithium and tetravinyltin and the formation of a-dialkylamino organolithium compounds from the corresponding organotin compounds ... 

There are several useful means for preparation of organomercury compounds. The general metal-metal exchange reaction between mercury(II) salts and organolithium or magnesium compounds is applicable. The oxymercuration reaction discussed in Section... 

Although the subject of exchange reactions of organolithium compounds has recently been dealt with in detail (14, 15), a brief account is included here because of the many reactions between these compounds and the alkyl derivatives of Groups II and III. 

Kauffmann reported the first tellurium-lithium exchange reaction of a vinylic telluride with an organolithium compound.255 Phenyl vinyl telluride 168 was deprotonated by lithium dicyclohexylamide (LDCA) in THF, and the resulting vinyl anion 169 was reacted with chlorotrimethylsilane to give telluride 170. Vinylsilane telluroacetal 170 was then reacted with phenyllithium to give the corresponding vinyllithium, which was captured with chlorotrimethylsilane to give the bis-silylated ethane 171 (Scheme 96).255... 

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