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 nucleophilicprolinecatalysis 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