A novel method for the synthesis of nicotinonitrile and diazepin derivatives under microwave irradiation

Ethyl 2-aryl-3-dimethylamino-acrylates 2a,b were prepared via the reaction of ethyl arylacetate with N,N-dimethylformamidedimethylacetal (DMFDMA) under microwave irradiation. Reaction of 2a,b with malononitrile afforded the corresponding substituted malononitrile derivatives 4a,b, which underwent intramolecular cyclization in boiling acetic acid, containing a catalytic amount of ammonium acetate, to give unexpected products 2-amino-6-hydroxy-5-(4-nitrophenyl) nicotinonitrile derivatives 6. Whereas 2a reacted with o-phenylenediamines under microwave irradiation to yield diazepin-4-ol derivative 9. On the other hand, reacting the enaminoesters 2a,b with urea and thiourea, as nitrogen nucleophiles, by heating under microwave yielded the pyrimidinone derivatives 12a–d.