Investigation of condensation products of aldehydes with acetoacetic ester catalyzed by organic bases: absolute configuration determination by X-ray crystallography and tautomeric equilibria studies by NMR spectroscopy

Investigation of condensation products of aldehydes with acetoacetic ester catalyzed by organic... Two condensation products of aldehydes with acetoacetic ester catalyzed by methylamine or piperidine, 3a and 3b, were unambiguously assigned by single-crystal X-ray diffraction. Their X-ray crystallographic observations in the solid state and the NMR analysis ever-reported in solution phase, which were complementary to each other, were compared for an in-depth study of reliable geometrical or conformational information of poly-substituted β-keto esters 3a–e, and good agreement is observed between them. Furthermore, keto–enol tautomeric equilibriums of β-keto esters 3a–e have also been investigated using NMR spectroscopy. The results indicated that β-keto esters 3a–e exist as a mixture of keto and enol isomers in chloroform solutions when giving sufficient time at room temperature. The equilibriums were on the side of the keto tautomer with the ratio [enol]/[keto] ranging from 0.11 to 0.66. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Research on Chemical Intermediates Springer Journals

Investigation of condensation products of aldehydes with acetoacetic ester catalyzed by organic bases: absolute configuration determination by X-ray crystallography and tautomeric equilibria studies by NMR spectroscopy

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Publisher
Springer Netherlands
Copyright
Copyright © 2014 by Springer Science+Business Media Dordrecht
Subject
Chemistry; Catalysis; Physical Chemistry; Inorganic Chemistry
ISSN
0922-6168
eISSN
1568-5675
D.O.I.
10.1007/s11164-014-1700-z
Publisher site
See Article on Publisher Site

Abstract

Two condensation products of aldehydes with acetoacetic ester catalyzed by methylamine or piperidine, 3a and 3b, were unambiguously assigned by single-crystal X-ray diffraction. Their X-ray crystallographic observations in the solid state and the NMR analysis ever-reported in solution phase, which were complementary to each other, were compared for an in-depth study of reliable geometrical or conformational information of poly-substituted β-keto esters 3a–e, and good agreement is observed between them. Furthermore, keto–enol tautomeric equilibriums of β-keto esters 3a–e have also been investigated using NMR spectroscopy. The results indicated that β-keto esters 3a–e exist as a mixture of keto and enol isomers in chloroform solutions when giving sufficient time at room temperature. The equilibriums were on the side of the keto tautomer with the ratio [enol]/[keto] ranging from 0.11 to 0.66.

Journal

Research on Chemical IntermediatesSpringer Journals

Published: May 25, 2014

References

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