Synthesis of 1,2,3,4,6,7,8,9-octahydropyrimido[4,5-b]quinoline-2,4-dione

In the presence of hydrazine hydrate or sodium ethylate, ethyl 2-(N-phenylcarbamoyl)amino]-5,6,7,8-tetrahydroquinoline-3-carboxylate is converted to 3-amino- or 3-phenyl-1,2,3,4,6,7,8,9-octahydropyrimido4,5-b]quinoline-2,4-dione. Compounds analogous to the latter are also obtained during heating of 2-amino-5,6,7,8-tetrahydroquinoline-3-carboxylic arylamides with phenyl isocyanate or from their N-phenylcarbamoyl derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1114–1117, August, 1989.