Direct Generation of N‐Alkoxycarbonyl Nitrones from Oximes: Intramolecular Cycloaddition of Oximes Having Alkene Moieties

Abstract

Abstractδ,ϵ‐Unsaturated oximes, on heating with O‐alkyl S‐(pyridin‐2‐yl)carbonothioates (PySCO2R) in refluxing toluene, undergo intramolecular cycloaddition to give N‐alkoxycarbonylated multi‐cyclic compounds. Mechanistic studies indicate that the reaction involves direct generation of N‐alkoxycarbonyl nitrones followed by cycloaddition, instead of intramolecular oxime‐olefin cycloaddition (IOOC) followed by alkoxycarbonylation. DFT calculation indicates that N‐alkoxycarbonylation of oxime with PySCO2R is a concerted reaction. The reaction of oxime with a chiral alkoxycarbonylation reagent exhibits a reasonably high diastereo‐face selectivity.