Iminophosphorane 1 reacted with an aromatic isocyanate to unexpectedly give a mixture of carbodiimides 2, 3 and 4 through both the normal and the abnormal aza-Wittig reactions. 3-Aminoimidazolone 10 was obtained from the reaction of hydrazine hydrate with carbodiimide 2. Reaction of 10 with triphenyphosphane, hexachloroethane and triethylamine produced iminophosphorane 11 in good yield. A tandem aza-Wittig reaction of iminophosphorane 11 with isocyanate or CS2 generated 3,5-dihydro-6H-imidazo[1,2-b]-1,2,4-triazol-6-ones 13 or 15 in satisfactory yield. Carbodiimides 18, obtained from normal aza...
