2,9-Dimethyl-3-ethyl-4-oxo-4H-pyrido(1,2-a)pyrimidine hydrochloride 2,9-Dimethyl-3-ethyl-4H-pyrido(1,2-a)pyrimidin-4-one monohydrochloride 4H-Pyrido(1,2-a)pyrimidin-4-one, 2,9-dimethyl-3-ethyl-, monohydrochloride 80310-21-0