GUANIDINE-ANNELATED HETEROCYCLES XVI. A PRACTICAL SYNTHESIS OF 7-CHLORO-4-PHENYLAMINO[1,2,4]TRIAZOLO-QUINAZOLIN-5(4H)-ONES

The triazolo[2,3-a]quinazolin-5(4H)-ones 9a-c can be prepared via Dimroth rearrangement by treatment of 5 with representative carboxylic acid orthoesters 6a-c each heating at 40 °C more elevated temperature than the preparation of their analogous triazolo[4,3-a] isomers 7a-c.