Thermal Fragmentation and Rearrangement of 3-phenyl-4-aryl-5-phenylimino-1,2,4-oxadiazoline Derivatives

Thermal fragmentation of 3-phenyl-4-aryl-5-phenylimino-1,2,4-oxadiazolines I and II (Ar= Ph, p-tolyl) in a sealed tube under nitrogen gives rise to benzonitrile, arylamines, anilides, phenols, arylureas, and benzimidazole derivatives. In the presence of naphthalene as solvent, I gave α- and β-naphthols beside the previous products. Also, heating of I under reflux in boiling anhydrous tetraline lead to the formation of 1-hydroxytetraline, α-tetralone and 1,1’-bitetralyl as the major products. The isolated products have been interpreted in term of a free radical mechanism involving the homolysis of N-O and/or C-N bond