Two new pyrimido-1, 4-diazepine derivatives, 4-phenyl-6, 8-dimethyl-1H-pyrimido-[4, 5-b] [1, 4] diazepine-2, 7, 9 (3H, 6H, 8H) trione (VIII) and 2-phenyl-6, 8-dimethyl-3H-pyrimido [4, 5-b] [1, 4] diazepine-4, 7, 9 (5H, 6H, 8H) trione (X), were synthesized. 5, 6-Diamino-1, 3-dimethyluracil (I) was condensed with ethyl acetoacetate under elimination of ethanol by heating in xylene, to give N-(6-amino-1, 3-dimethyl-2, 4-dioxo-1, 2, 3, 4-tetrahydro-5-pyrimidyl)-3-phenyl-3-oxopropionamide (VI). When the two components were heated in butanol, I gave ethyl 3-phenyl-3-(6-amino-1, 3-dimethyl-2, 4-dioxo-1, 2, 3, 4-tetrahydro-5-pyrimidylamino) acrylate (IX) under elimination of water. Heating of VI at 230-240°for a few minutes under a reduced pressure gave VIII in a poor yield (17%), while heating of IX in ethanol with sodium ethoxide on a water bath for a few minutes gave X in a good yield (74%).
