Structure of Acyllithium

The structure of acyllithium has not yet been established experimentally. A priori, three types of structures can be envisioned. These are acyllithium (or 1/ -acyllithium), / -acyllithium and lithioxy carbene. For the case of lithioxy carbene, the 

Carbamoyllithium is a nitrogen analog of acyllithium and a broadly defined carbonyl anion which has been the subject of extensive study. 

One of the characteristics of these species is that they are more stable than acyllithium. Examples, which are shown in Eqs. (5.66) to (5.70) [77-82] illustrate interesting features of carbamoyllithium. A detailed discussion, however, is beyond the scope of this review. 

AcylHthium derivatives represent exotic molecules. In contrast to the acyl cation or acylinium ion, which is a well-documented species, acyllithium (or acylmagne-sium etc.) derivatives are not discussed in depth in books on organic chemistry. As seen above, the rich chemistry of acyllithium is now available, and further development of the chemistry of this quite reactive and unique species is expected in the future. 

We wish to acknowledge our able co-workers whose names are shown in the references. Without their collaboration this chapter would not have been possible. 

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