Hydrocarbons polylithiation

Maercker, A., Theis, M. Some Aspects of the Chemistry of Polylithiated Aliphatic Hydrocarbons, 138, 1-61 (1986). 

Some Aspects of the Chemistry of Polylithiated Aliphatic Hydrocarbons... 

Numerous polylithiated aliphatic hydrocarbons have been prepared by polymetalation of the corresponding hydrocarbons and only a few characteristic examples can be given. 

In contrast, isocentric polylithiated hydrocarbons often show reactivities quite atypical for normal lithiumorganic compounds. Already in 1971 Krohmer and Gou-beau reported that dilithiomethane 3 reacts with chlorotrimethylsilane only under forced conditions — 48 hours at 150 °C in a sealed tube — which is rather unusual for an alkyllithium compound. We found that -the reaction can be performed much more conveniently by refluxing CHjLij in McjSiCI in the absence of a solvent, but anyhow it needs four days to be complete... 

No reaction of dilithiomethane with benzaldehyde and benzophenone in diethyl ether could be detected even after two days at room temperature. With aliphatic ketones e.g. ethyl methyl ketone, on the other hand, only the products of aldol addition and aldol condensation have been found showing that CH Li acts as a base and not as a nucleophile . Carbonyl compounds therefore cannot be used in order to characterize isocentric polylithiated hydrocarbons. 

The few other known X-ray structures of polylithiated aliphatic hydrocarbons are also in agreement with theoretical results as far as calculations on these systems have been performed at all. 

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