Double diastereoselection in asymmetric [2+3] cycloaddition of chiral oxazoline N-oxides: application to the kinetic resolution of a racemic α,β-unsaturated δ-lactone - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Tetrahedron: Asymmetry Année : 1999

Double diastereoselection in asymmetric [2+3] cycloaddition of chiral oxazoline N-oxides: application to the kinetic resolution of a racemic α,β-unsaturated δ-lactone

Résumé

The asymmetric [2+3] cycloaddition reaction between chiral oxazoline N-oxide 1 and , -unsaturated lactone 2 was studied. A double diastereoselection was observed, (1R)-1 and (R)-2 gave a mismatched pair with almost no cycloadduct obtained. A transition state model is proposed, accounting for the destabilization of transition state in the cycloaddition reaction. This result has led to kinetic resolution studies, in which both enantiomers of 1 were reacted with racemic lactone 2. The enantiomeric excess of the recovered lactone 2was determined to be up to 70% ee, by 13C-{1H} NMR analysis in a chiral liquid crystalline solvent. The experimental results are in agreement with predicted enantiomeric excesses and consistent with the transition state models.

Dates et versions

hal-02309107 , version 1 (09-10-2019)

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Citer

Olivier Dirat, Cyrille Kouklovsky, Yves Langlois, Philippe Lesot, Jacques Courtieu. Double diastereoselection in asymmetric [2+3] cycloaddition of chiral oxazoline N-oxides: application to the kinetic resolution of a racemic α,β-unsaturated δ-lactone. Tetrahedron: Asymmetry, 1999, 10 (16), pp.3197-3207. ⟨10.1016/S0957-4166(99)00317-1⟩. ⟨hal-02309107⟩
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