Synthesis and Photochemistry of 3-(o-Stilbeneyl)-4-H/Me/Ph-sydnones ; Intramolecular Cyclization to 1, 2- Benzodiazepines and/or Quinolines

Stilbeneylsydnone derivatives were synthesized by a sequence of reactions in good yields. Irradiation of 3-stilbeneyl-4-methylsydnone 4 gives 1H-1, 2-benzodiazepine derivative 7 as the main product along with 2-methylquinoline derivative 20. Irradiation of 3-stilbeneyl-4-phenylsydnone 5 afforded only 1H-1, 2-benzodiazepine derivative 8 whereas on irradiation of 4-unsubstituted 3-stilbeneylsydnone 3 no benzodiazepine derivative was detected. An efficient novel photochemical approach to 1H-1, 2-benzodiazepines has been found from the new 3-(o-stilbeneyl)-4-substituted-sydnones via intramolecular 1, 7-electrocyclization reaction of the photogenerated nitrile imines.