Studies on the Syntheses of N-Heterocyclic Compounds. X. Syntheses of 2-Phenyl-pyrazino[2, 3-d]pyridazine Derivatives

Abstract

Chlorination of 2-phenyl-5, 6, 7, 8-tetrahydropyrazino[2, 3-d]pyridazine-5, 8-dione (3) gave 2-phenyl-5, 8-dichloropyrazino[2, 3-d]pyridazine (10) in a high yield. Treatment of 10 with an aliphatic amine gave a mixture of the isomeric monoamino compounds (16 and 17). Probably due to the resonance effect of 2-phenyl group, chlorine atoms at both 5 and 8 were readily substituted by various nucleophiles to give disubstituted products (27).