2-Chloro-5,6,7,8-tetrahydro-pyrido[4,3-d]pyriMidine Hydrochloride; 2-chloro-5H,6H,7H,8H-pyrido[4,3-d]pyrimidine hydrochloride; Pyrido[4,3-d]pyrimidine, 2-chloro-5,6,7,8-tetrahydro-, hydrochloride (1:1);