Synthesis of new imidazo[4,5-d][1,3]diazepine derivatives from 5-amino-4-(cyanoformimidoyl)imidazoles

Article abstract of DOI:10.1002/jhet.5570330352

N¹-[(Z)-2-Amino-1,2-dicyanovinyl]formamidines 1a-d react readily with tosyl isocyanate to form novel 8-amino-3-substituted-5-oxo-7-tosylaminoimidazo[4,5-d][1,3]diazepines 6a-d rather than the 6-cyano-2-oxopurine derivatives 5a-d expected. Compound 5a has been synthesized from 1a by reaction with ethyl chloroformate and base-catalyzed cyclization of the resultant 5-ethoxycarbonylamino-4-(cyanoformimidoyl)imidazole. Treatment of the 5-amino-4-cyanoimidazoles 7a and b with tosyl isocyanate under similar conditions gives the 4-cyano-5-(3′-tosylureido)imidazoles 8a and b, which on treatment with ethanolic ammonia cyclizes to the corresponding isoguanines 10a and b.