Synthesis and properties of 3-arylcyclohepta[4,5]-pyrrolo[1,2-a]-1,3,5-triazine-2,4(3H)-diones and related compounds : Photo-induced autorecycling oxidation of amines

3-Phenyl- and 3-(4-nitrophenyl)cyclohepta[4,5]pyrrolo[1,2-a]-1,3,5-triazine-2,4(3H)-diones and the corresponding arylimino derivatives (5a,b) and (6a,b) were synthesized by the reaction of (l-azaazulen-2-yl)imino-triphenylphosphorane with aryl isocyanates and subsequent heterocyclization reaction with a second isocyanate. Related cation (lla), which was derived from methylation of 5a, is also prepared. The electrochemical reduction of these compounds exhibited more negative reduction potentials as compared with the related compounds. Some of these compounds underwent a photo-induced autorecycling oxidation toward some amines to give the corresponding imines in more than 100% yield.