This work was supported by the DFG (SPP 1179). Scholarships by the Cusanuswerk and the Studienstiftung des deutschen Volkes are gratefully acknowledged. We thank the anonymous referees of this manuscript for exceptionally helpful and constructive suggestions.
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Communication
The Elusive Enamine Intermediate in Proline-Catalyzed Aldol Reactions: NMR Detection, Formation Pathway, and Stabilization Trends†
Article first published online: 8 JUN 2010
DOI: 10.1002/anie.200906629
Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Additional Information
How to Cite
Schmid, Markus B., Zeitler, K. and Gschwind, Ruth M. (2010), The Elusive Enamine Intermediate in Proline-Catalyzed Aldol Reactions: NMR Detection, Formation Pathway, and Stabilization Trends. Angew. Chem. Int. Ed., 49: 4997–5003. doi: 10.1002/anie.200906629
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Publication History
- Issue published online: 29 JUN 2010
- Article first published online: 8 JUN 2010
- Manuscript Revised: 10 APR 2010
- Manuscript Received: 24 NOV 2009
Funded by
- DFG
Keywords:
- aldol reaction;
- enamines;
- NMR spectroscopy;
- organocatalysis;
- proline catalysis
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 solvent and substitution pattern on the aldehyde is presented.