beta-enaminoesters as building blocks in heterocyclic synthesis. A novel synthesis of fused azines by using Blaise reaction as a key step

Ethyl bromoacetate 4 reacts with nitriles in the presence of activated zinc dust to afford the beta-enaminoesters 7 and 19. Compounds 7 and 19 show hi gh reactivity towards a variety of reagents to give polyfunctional heterocy clic compounds. For example. the enaminoesters 7 and 19 react with benzalde hyde to give the 1,4 dihydropyridine derivatives 9 and 20, respectively. Is othiocyanates 24 (R = Ph, Oft) added to 19 to furnish pyrimidine-thiones 26 and 27 respectively. Structures and conceivable mechanisms are discussed.