21271-35-2 Butyric acid, 2-((4-oxo-3-phenyl-4H-pyrazino(1,2-a)pyrimidin-2-yl)oxy)-, ethyl ester Ethyl 2-((4-oxo-3-phenyl-4H-pyrazino(1,2-a)pyrimidin-2-yl)oxy)butyrate