Abstract
The title compounds were prepared via reacting diethyl 2-cyano-4-dimethylamino-methylene-3-methylpent-2-enedioic acid 2 with hydrazine hydrate and with ethyl amine. The formed pyridones 3a condensed with dimethylformamide dimethyl acetal to yield the corresponding enamine 4 that could be cyclised into the pyrido[3,4-c]pyridine 5 by reflux in acetic acid in presence of ammonium acetate. The reaction of 3a with elemental sulfur afforded the thienopyridine 6 that reacted readily with electron poor olefins and acetylenes to yield isoquinolines 8, 10 and 11. Compound 3a reacted with benzylidene-malononitrile to yield the isoquinoline 14.