The carbodiimides 3, obtained from aza-Wittig reactions of iminophosphorane 2 with aromatic isocyanates, reacted with hydrazine to give selectively 3-amino-2-arylaminobenzofuro[3,2-d]pyrimidin-4(3H)-ones 5. Reactions of 5 with triphenylphosphine, hexachloroethane and triethylamine produced iminophosphoranes 6. A tandem aza-Wittig reaction of iminophosphorane 6 with isocyanate or acyl chloride generated previously unreported tetracyclic benzo[4,5]furo[3,2-d]-1,2,4-triazolo[1,5-a]py...
