Pyridopyrimidines. Part V. Syntheses and properties of pyrido[3,4-d]-pyrimidin-4(3H)-ones and -pyrimidine-2,4-(1H,3H)-diones

Abstract

2,6,8-Trimethyl-, 6,8-dimethyl-2-phenyl-, and 2-phenyl-pyrido[3,4-d][1,3]oxazin-4-ones have been prepared from the corresponding 3-aminopyridine-4-carboxylic acids. Treatment of the pyrido-oxazines with amines yielded the corresponding pyrido[3,4-d]pyrimidines or intermediate 3-aminopyridine-4-carboxamides. Hydrazinolyses and methylations of a number of pyrido[3,4-d]pyrimidin-4(3H)-ones and -pyrimidine-2,4(1H,3H)-diones are described. Some n.m.r. and mass spectra are discussed.