Intramolecular6-exoCyclization of 1-Nitro-6-heptenyl Radicals Generated by One-Electron Oxidation ofAci-Nitroanions with CAN: A Completely Stereoselective Formation of 2,3,4-Trisubstituted Tetrahydropyrans

Abstract

Upon one-electron oxidation by ammonium hexanitratocerate (IV) (CAN), aci-nitroanions 3a-d resulting from oxa-Michael addition of homoallylic alcohol to a,b-disubstituted nitroalkenes 1a-d undergo radical cyclization to afford stereoselectively 2,3-dialkyl-4-methyl tetrahydropyrans 6a-d.