Catalytic enantioselective synthesis of carboxy-substituted 2-isoxazolines by cascade oxa-Michael-cyclization?

Organic & Biomolecular Chemistry Pub Date: 2018-01-02 DOI: 10.1039/C7OB02722B

Abstract

An efficient quinidine-based phase-transfer-catalyzed enantioselective cascade oxa-Michael-cyclization reaction of hydroxylamine with various β-carboxy-substituted α,β-unsaturated ketones has been achieved for the preparation of chiral carboxy-substituted 2-isoxazolines. This cascade reaction provided the desired products in good yields (up to 98%) with excellent enantioselectivities (91–96% ee). In addition, the cascade reaction was effectively applied to the first catalytic asymmetric synthesis of the herbicide (S)-methiozolin.

Graphical abstract: Catalytic enantioselective synthesis of carboxy-substituted 2-isoxazolines by cascade oxa-Michael-cyclization
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