The configurational stability of chiral lithio α-amino carbanions. The effect of Li-O vs. Li-N complexation.
1994; Elsevier BV; Volume: 50; Issue: 20 Linguagem: Inglês
10.1016/s0040-4020(01)90460-0
ISSN1464-5416
AutoresTodd R. Elworthy, A. I. Meyers,
Tópico(s)Chemical Reaction Mechanisms
Resumoα-Lithio pyrrolidine, as its N-t-BOC or formamidine derivative, has been generated in high enantiomeric purity via Sn-Li exchange of the enantiomerically enriched (88-95°) α-tributylstannane derivative, 4. The alkylation of these lithio carbanions gave 2-methyl pyrrolidines as well as providing a measure of their configurational stability. It was found that the α-lithio formamidines were configurationally more stable than the t-BOC derivatives and this is attributed to the stronger O-Li bond which weakens the adjacent C-Li bond, thus allowing configurational decay to occur more readily. This is the first report wherein a difference is observed between O-Li-C and N-Li-C configurational stability.
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