Novel generation and cycloaddition reactivity of N-phenylsulfonylbenzonitrilimine via thermal decomposition of N-(phenylsulfonyl)benzohydrazonoyl chloride

Thermal decomposition of N(phenylsulfonyl)-benzohydrazonoyl chloride (1) in refluxing toluene generated N-phenylsulfonylbenzonitrilimine (2) which gave 1,3-dipolar cycloadducts with ethyl (4a) and methyl acrylate (4b), acrylonitrile (4c), styrene (4d), norbornene (4e), and norbornadiene (4f). The reactions with 4a–d, 2 afforded regiospecifically 5-R substituted pyrazolines 5a–d in lower yields. The raction of 2 with 4e gave only exo adduct 5e, while the reaction with 4f gave both exo- (5f_x) and endo adducts (5f_n) as well as their retro-Diels-Alder product 6.