Oxidation of aminoalkyl and hydroxylaminoalkyl furans

The oxidation reactions of amino and hydroxylamino substituted alkylfurans were explored for the synthesis of structurally complex compounds from simple starting materials. A novel photooxygenation of the furan derivatives gave an alpha,beta-unsaturated dicarbonyl moiety which underwent subsequent conjugate addition to yield diastereomeric mixtures of the corresponding pyrrolidine and isoxazoline heterocycles. Oxidation of the alpha,beta-unsaturated dicarbonyl using mCPBA gave epoxide intermediates, which were opened by nucleophilic attack of the amino groups, furnishing pyrrolidine and isoxazolidine heterocycles. (C) 2015 Elsevier Ltd. All rights reserved.