REACTION OF N-UNSUBSTITUTED IMIDAZOLES WITH BENZONITRILE OXIDE

The behaviour of N-unsubstituted imidazoles 1 with benzonitrile oxide is reported. The results indicate that in solution a ring-chain tautom erism exists between the cycloadduct 3B and the Z-oxime 3A; while in t he solid state only the chain form 3A was observed. Oximes of N-benzoy limidazol-2-ones 4, derived from subsequent attack of the 1,3-dipole o n both tautomers, and 3,6-diphenyl-1,4,2,5-dioxadiazine 2, an unusual dimer of the benzonitrile oxide, were also isolated. A mechanism invol ving a zwitterionic intermediate is proposed. The structure of the oxi mes of N-benzoylimidazol-2-one 4 and 10, derived from benzonitrile oxi de and p-toluonitrile oxide respectively, was determined by X-ray diff raction analysis.