3 Tetrazolylpyridopyrimidin 4 one derivatives useful as {HEAD ~ an antiallergy agent} are produced by reacting a cyano derivative of pyridopyrimidin 4 one compound with hydrazoic acid, followed by hydrolysis, or with a salt of hydrazoic acid, reacting {TAIL ~ the resulting product} with an acid or a base, followed by hydrolysis 
3 Tetrazolylpyridopyrimidin 4 one derivatives useful as { HEAD ~ an antiallergy agent } are produced by reacting a cyano derivative of pyridopyrimidin 4 one compound with hydrazoic acid , followed by hydrolysis , or with a salt of hydrazoic acid , reacting { TAIL ~ the resulting product } with an acid or a base , followed by hydrolysis
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH