Friary, R; McPhail, AT; Seidl, V, "Novel Syntheses of Tricyclic, N-Aryl, Pyridine- and Pyrazine-Fused Pyrimidones", Collection of Czechoslovak Chemical Communications, 1993, 58(5), 1133-1150, Institute of Organic Chemistry & Biochemistry [Gateway.cgi], [doi].
(last updated on 2026/01/21)
Abstract:
2-methylthio-2-imidazoline and 2-methylthio-1,4,5,6-tetrahydro-2-pyrimidine amidated 2-chloro-3-pyridine- and 2-chloro-3-pyrazinecarbonyl chlorides. The products reacted with aromatic amines forming a series of tricyclic, linearly fused N-aryl pyrimidones. Included among these pyrimidones were 10-aryl-2,3-dihydroimidazo[1,2-a]pyrido[2,3-d]pyrimidin-5(10H)-ones, 11-aryl-2,3,4,11-tetrahydropyrido-[2,3-d]pyrimido[1,2-a]pyrimidin-6(6H)-ones, 10-aryl-2,3-dihydroimidazo[1,2-a]pyrazino[2,3-d]pyrimidin-5(10H)-ones and 11-aryl-2,3,4,11-tetrahydropyrimido-[1,2-a]pyrazino[2,3-d]pyrimidin-6(6H)-ones. 4,5,6,7-Tetrahydro-2-(mythylthio)-1H-1,3-diazepine amidated the ethyl hydrogen carbonate of 2-(phenylamino)-3-pyridinecarboxylic acid, forming 12-phenyl-2,3,4,5-tetrahydropyrido[2',3':4,5]pyrimido[1,2-a][1,3]diazepine-7(12H)-one. A single crystal X-ray analysis and an unambiguous synthesis established the structure of the linearly fused isomer 10-phenyl-2,3-dihydroimidazo[1,2-a]pyrido[2,3-d]pyrimidin-5(10H)-one.