We will investigate structure-reactivity relationships in N-lithiated species by focussing upon five lithium amides: lithium 2,2,6,6- tetramethylpiperidide (LiTMP), lithium hexamethyldisilazide (LiHMDS), lithium diisopropylamide (LDA), lithium diethylamide (Et2NLi), and lithium tetramethyldisilazide (LiTMDS). 6Li-15N double labelling spectroscopic methods can now provide aggregation and solvation states, relative free energies and enthalpies of solvation, and even mechanisms of ligand substitution. The detailed structural and energetic data for lithium amides complexed by a variety of mono- and bidentate ethereal and amine solvents will lay foundations for studying reactivity. Similarly, investigation of extremely sensitive solvent-dependent mixed aggregate equilibria will further our understanding of mixed aggregation as well as establish a structural foundations for the development of asymmetric reactions based upon mixed aggregation effects. Efforts to understand the chelate effect and to develop the chemistry of triple ions ([R2N-Li-NR2]- I/+LiS4 and (R2N-Li-X]-//+LiS4) will be prominent. We will continue to emphasize the correlation of solvation energy, aggregate structure, and reactivity through detailed mechanistic and rate studies of four synthetically important reactions of lithium amides: (1) ketone enolization, (2) imine metallation, (3) epoxide and alkyl halide elimination, and (4) orthometallation. - Significant progress is assured by substantial preliminary results and the mechanistic transparency of these particular reactions. Overall, the lithium amides offer the most promising opportunity to understand the complexities presented by organolithium chemistry.
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