Aluminum compounds natural products synthesis

Enolates are undoubtedly the most versatile intermediates for C-C, C-N, C-O bond-forming reactions [36]. Continuous progress has been made not only in fundamental operations involving these anionic species but also during the synthesis of complex natural products. Compared with metal enolates with counter cations of, e.g., B, Si, Li, Na, K, Mg, Ti, Sn, Cu, etc., aluminum enolates have found fewer apphcations, probably because no particular advantages over the other metals have been perceptible. There are, however, still intriguing aspects of novel reactivity and selectivity in the formation and reaction of aluminum enolates. Specifically, very recent development have highhghted pre-formation of Lewis acid-carbonyl complexes by use of bulky aluminum compounds as precursors of aluminum enolates the behavior of these complexes is unprecedented. 

Note that whether one, two or three X groups are displaced depends on the amount of organometallic reagent used, on the nature of X and R, and on the reaction temperature. Alkyl-aluminum compounds are useful for the synthesis of trialkylboranes, while organostannous compounds usually result in monosubstitution products. 

---