Study on the 1,3-dipolar cycloaddition reaction of 4-ethoxy-1,1,1-trifluoro-3-buten-2-one with nitrile oxides

Abstract 1,3-Dipolar cycloaddition (1,3-DC) reaction of 4-ethoxy-1,1,1-trifluoro-3-buten-2-one 1 with nitrile oxides was studied. It was found that besides its C C participating in the formation of isoxazole rings, trifluoromethyl activated C O also underwent 1,3-DC reaction with nitrile oxides to afford 1,4,2-dioxazole rings. Single crystal diffraction analysis also evidenced the diheterocyclic configuration.