2-Oxo-3-phenyl-1,2,3,4-tetrahydropyrido(2,3-c)pyrazine 3,4-Dihydro-3-phenylpyrido(3,4-b)pyrazin-2(1H)-one 43064-15-9 Pyrido(3,4-b)pyrazin-2(1H)-one, 3,4-dihydro-3-phenyl-