Synthesis of 6,6-Disubstituted Tetrahydrothiopheno(3,4-c)isoxazolines from β-Nitroenones.

Abstract β-Nitrosulfides 2, formed by Michael addition of prop-2-en-1-thiol to β-nitroenones 1 in the presence of a catalytic amount of triethylamine, undergo either Intramolecular Nitrile Oxide Cycloadditions (INOC) or Intramolecular Silylnitronate Cycloadditions (ISOC) to functionalized 6,6-disubstituted tetrahydrothiopheno [3,4-c] isoxazolines 3 and 4. The stereoselectivity, poor by the INOC reactions starting from acyclic β-nitroenones, is markedly increased with the ISOC procedure.