The Elusive Enamine Intermediate in Proline-Catalyzed Aldol Reactions: NMR Detection, Formation Pathway, and Stabilization Trends
作者:Markus B. Schmid、Kirsten Zeitler、Ruth M. Gschwind
DOI:10.1002/anie.200906629
日期:——
The missing link: The elusive enamine intermediate of nucleophilic proline catalysis was detected and stereochemically characterized by NMR analysis of the aldehyde self‐aldolization reaction in dipolar aprotic solvents. NMR exchange spectroscopy (EXSY) was used to observe direct enamine formation from oxazolidinones. Additionally, the stabilization of the intermediate by the appropriate choice of
缺失的环节:检测到了亲核脯氨酸催化的难以捉摸的烯胺中间体,并通过NMR分析了偶极非质子传递溶剂中醛的自醛缩合反应的立体化学特征。NMR交换光谱法(EXSY)用于观察由恶唑烷酮直接形成烯胺。另外,中间的由醛和溶剂取代模式选择适宜的稳定化呈现。