Preparation of fused [1,3,5] benzotriazepines by a tandem aza wittig/carbodiimide-mediated annelation reaction

Article abstract of DOI:10.1016/0040-4039(91)80667-U

AzaWittig type reaction of bis(iminophosphorane) 2, available from the diazide 1 and triphenylphosphine, with one mole of isothiocyanate leads to the iminophosphoranes 3 derived from the [1,2 ,4 ]triazolo[2,3-b] indazole ring, which by treatment with a se