2-Methyl-3-ethyl-4-oxo-4H-pyrido(1,2-a)pyrimidine hydrochloride 3-Ethyl-2-methyl-4H-pyrido(1,2-a)pyrimidin-4-one monohydrochloride 4H-Pyrido(1,2-a)pyrimidin-4-one, 3-ethyl-2-methyl-, monohydrochloride 70381-33-8