Synthesis of Novel 6-Cyano-9-(aryl)-9H-purine Derivatives Via Formamidine Intermediates

Novel 9-substituted cyanopurine derivatives (4a-d) were synthesized in three steps in high yield. Diaminomaleonitrile (1) reacted with triethyl orthoformate to afford (Z)-N-[2-amino-1,2-dicyanovinyl] formimidate (2) which was converted to aryl-(Z)-N-[2-amino-1,2-dicyanovinyl] formamidines (3a-d) in the presence of a catalytic amount of anilinium chloride and aromatic amines in ethanol at room temperature under inert atmosphere (Argon). Furthermore, the reaction of (3a-d) with triethyl orthoformate afforded novel 6-cyano-9-(aryl)-9H-purine derivatives (4a-d) which can be used without further purification. All compounds have been fully characterized by spectroscopic data