Synthesis and reaction of cyano-substitued 1,2,4-trioxolanes

Carbonyl oxides, derived from the ozonolyses of vinyl ethers, readily undergo [3 + 2] cycloadditions with acyl cyanides affording the corresponding cyano-substituted 1,2,4-trioxolanes in isolated yields of 34–88%. In competition experiments, a relative order of reactivity of the carbonyl oxide trapping agents was tentatively deduced; trifluoroacetophenone > α,α-diphenyl-N-methylnitrone (N-methyldiphenyl-methylideneamine N-oxide) > benzoyl cyanide > methyl benzoylformate > α,α,N-triphenylimine [N-(diphenylmethylidene)aniline] benzaldehyde. As expected from the electron-withdrawing ability of the cyano group, 3-cyano-3-phenyl-1,2,4-trioxolane oxidized not only triphenylphosphine but also methyl p-tolyl sulfide and 2,3-dimethylbut-2-ene very easily.