SYNTHETIC APPLICATIONS OF C,C-BIS(IMINOPHOSPHORANES) - PREPARATION OF [5+5] RIGID BICYCLIC GUANIDINES AND 1,3,6-BENZOTHIADIAZEPINO[3,2-A] BENZIMIDAZOLE DERIVATIVES

Aza Wittig-type reaction of bis(iminophosphorane) 1, derived from bis(2-aminophenyl)amine with two equivalents of isocyanate directly provided benzimidazo[1,2-a]benzimidazole derivatives 2. However, the reaction with one equivalent of isocyanate or carbon disulfide afforded C-aryl iminophosphoranes 3 or 6, respectively, derived from the 1-phenylbenzimidazole ring, which underwent cyclization by the action of one equivalent of isocyanate to give the [5+5] rigid bicyclic guanidines 2 or 1,3,6-benzothiadiazepino[3,2-a] benzimidazoles 8.