Mechanistic studies of hydrazide-catalyzed enantioselective Diels-Alder reactions

Journal of Organic Chemistry

Volumn 71, Issue 12, 2006, Pages 4663-4666

  Lemay, Mathieu ^a   Ogilvie, William W ^a  

^a UNIVERSITY OF OTTAWA   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

CATALYSIS; HYDROLYSIS; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; REACTION KINETICS; THERMODYNAMIC PROPERTIES;

ALDER REACTION; DIELS-ALDER CYCLOADDITION; THERMODYNAMIC COMPONENTS;

ORGANIC COMPOUNDS;

ACID; ALDEHYDE; ALKADIENE; CINNAMALDEHYDE; CYCLOPENTADIENE DERIVATIVE; HYDRAZIDE; TRIFLUOROMETHANESULFONIC ACID; WATER;

ARTICLE; CARBON NUCLEAR MAGNETIC RESONANCE; CATALYSIS; CYCLOADDITION; DIELS ALDER REACTION; ENANTIOSELECTIVITY; HYDROLYSIS; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; POLYMERIZATION; PROTON TRANSPORT; SOLVENT EFFECT; STEADY STATE; THERMODYNAMICS;

EID: 33744900602     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo060339p     Document Type: Article

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25. Only the major enantiomers are shown.
26. 2 as solvent produced comparable yields (92%) and enantioselectivity (75% endo ee) to the fully aqueous process, and therefore, we carried out our mechanistic investigations in that solvent.
27. 2O. Performing the reaction at 0.01 M gave low conversion to 3 (65%, equilibration was still rapid). Increasing the concentration to 0.1 or 1.0 M resulted in rapid and complete conversion to 3.
28. At the conclusion of this experiment, the products were isolated in 88% yield and 83% ee (exo) and 81% ee (endo).
29. Control spectra for 3and 5-8 were independently collected.
30. Spectral overlap precluded the direct measurement of the concentration of 6 in the mixture. The amounts of this compound were obtained by subtraction and used to normalize the values in Figure 2.
31. After 16 h the amounts of all species were unchanged.
32. To simulate the normal forward process, 2 equiv of cyclopentadiene was added.
33. When a stoichiometric amount of catalyst was used, changes in the ratio of diastereomers were more pronounced (from 1.7:1 to 1:1 endo:exo).
34. 2O for 24 h.
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37. This is supported by the observation that the enantioselectivities for the entire process were not dependent on the relative amounts of catalyst and acid. See ref 4.