Synthesis of pyrido [3,2-d] pyrimidines and pyrido [3,2-d] -1,2,4-triazolo [4,5-a or 5,4-b] pyrimidines

Reaction of 6-[1-piperidino or 1-pyrrolidino-carbony1-2, 8-dichloro-4-[1-piperidino or 1-pyrrolidino]-pyrido[3,2-d] pyrimidines [1a and b] with hydrazine hydrate afforded the corresponding 2-hydrazino derivatives [2a and b]. Treatment of 2a and b with nitrous acid or aromatic aldehydes furnished the corresponding azides [3 a and b] and arylidene derivatives [4 a-d], respectively. Pyrido[3,2-d]-1,2,4-triazolo[4,5-a or 5,4-b] pyrimidines [5a-d, E or A] were obtained either by oxidative cyclization of 4a-d with bromine in acetic acid or by acylative cyclization of 2a and b