3,6-Dimethyl-2-ethyl-4-oxo-4H-pyrido(1,2-a)pyrimidine hydrochloride 3,6-Dimethyl-2-ethyl-4H-pyrido(1,2-a)pyrimidin-4-one monohydrochloride 4H-Pyrido(1,2-a)pyrimidin-4-one, 3,6-dimethyl-2-ethyl-, monohydrochloride 70381-32-7