Within the next funding period we will continue our investigations of lithium dialkylamides and related lithioimine derivatives. With respect to the lithium amides, we will place particular emphasis on the chemistry of lithium 2,2,6,6-tetramethylpiperidide (LiTMP), lithium hexamethyldisilazide (LiHMDS), and lithium diisopropylamide (LDA). Using a combination of 6Li- 15N double labelling spectroscopic methods in conjunction with the recently developed 6Li-15N heteronuclear multiple quantum coherence (6Li-15N HMQC) spectroscopy we will investigate in detail influence of solvent and LiX structure on the complex mixed aggregate equilibria. Computational (MNDO and density functional theory) will play a role in elucidating some of the experimentally elusive details. We will continue to investigate the groundstate structures of ion triplets of general structure [R2N-Li-NR2]- //+Li(HMPA)4 as well as the mixed aggregate counterparts (e.g. [R2N-Li-X]- //+Li(HMPA)4). The progress made in the current funding period has established strong analytical and structural foundations upon which we will base additional mechanistic and rate studies of the reactions of N- lithiated species. We project that the rate studies will represent a substantially larger percentage of our effort in the upcoming funding period. Case studies to be investigated include: (1) N,N- dimethylhydrazone metallation, (2) orthometallation, (3) epoxide and alkyl halide elimination, (4) N- and C-alkylations of lithioimines, and (5) asymmetric reactions of lithium amides, lithioimines, and lithioimines derived from beta-ketoesters. A recently-constructed stopped-flow IR cell will undoubtedly be prominent in many of the rate studies.
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