Green Regioselective Synthesis of (Purin-6-yl)hydrazones

Some unique purine hydrazinylidene derivatives were synthesized by the regioselective reaction of 2,6-dichloropurine with hydrazine hydrate, followed by condensation with commercially available 1,3-dicarbonyl compounds according to a green chemistry approach. The structures of the synthesized compounds were confirmed by 1H and 13C NMR, IR, and mass spectra and elemental analyses. The regioselectivity of chlorine substitution in 2,6-dichloropurine was established by HMBC (Heteronuclear Multiple Bond Correlation) NMR technique.