Intramolecular cyclisations of nitrile imines bearing a thioether function

Abstract

N-Aryl nitrile imines bearing a thioether function in the ortho-position were generated in situ on treating the corresponding hydrazonyl chlorides with triethylamine in boiling benzene. In all cases, the major products were 4,1,2-benzothiadiazines arising from intramolecular participation of the sulphur and subsequent evolution of transient cyclic ylides. Minor products due to an intramolecular 1,3-dipolar cycloaddition were sometimes obtained.