Enantioselective Enolate Protonation with Chiral Anilines: Scope, Structural Requirements, and Mechanistic Implications
作者:E. Vedejs、A. W. Kruger、N. Lee、S. T. Sakata、M. Stec、E. Suna
DOI:10.1021/ja994437m
日期:2000.5.1
substitution at the γ-carbon, γ-protonation can be a competing reaction in the case of the aliphatic substrates 12, 14b, 14d, and 18. The evidence is most consistent with a mechanism that involves proton transfer from 1a to a mixed aggregate consisting of enolate 4a and the lithiated amide 5, but direct proton transfer from 1a to the enolate is not ruled out.
源自某些 β,γ 不饱和酸的 N,N-二异丙基酰胺(表 1,条目 1-4、7 和 10-13)的质子化已证明具有高对映选择性。根据双键几何结构和 γ-碳的取代度,在脂肪族底物 12、14b、14d 和 18 的情况下,γ-质子化可能是一种竞争反应。证据与涉及的机制最一致质子从 1a 转移到由烯醇化物 4a 和锂化酰胺 5 组成的混合聚集体,但不排除质子从 1a 直接转移到烯醇化物。