Organolithium compounds allyllithiums

Volume 8a of the Science of Synthesis series has reviewed the synthesis and applications in organic synthesis of the following organolithium compounds alkyl- and cycloalkyl-lithium,49 alkenyllithium,50 allyllithium,51 benzyllithium and (lithiomethyl) hetarenes,52 /-i-liihiocarboxylic acids and related compounds,53 and bis(organosulfan-yl)- and bis(organoselanyl)-methyllithium compounds.54... 

These arguments rested heavily on the results of the Mulliken population analysis. The Mulliken charge on Li for a variety of organolithium compounds ranges from about -fO.l to +0.5 (see Tables 23 and 24). Apparently, only partial transfer of charge occurs from lithium to carbon. The overlap population between carbon and lithium is large. For example, the overlap population between Cl and Li in allyllithium is +0.300. In 1,2-dilithioethene, where the... 

Although allylic lithiation by deprotonation of non-heterosubstituted compounds is possible using superbases (see section 2.6), in most cases allylic lithiation requires a directing heteroatom. (Non-heterosubstituted allyllithiums are best produced by reductive lithiation of allyl ethers or allyl sulfides - see section 4.4.) One of the few cases where this heteroatom is not a to the new organolithium is shown below the p-lithiation of a homoallylic amide 137. The reaction is particularly remarkable because of the possibility of competing deprotonation... 

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