Enaminones react with a variety of active methyl and methylene reagents in presence of ammonium acetate to yield functionally substituted pyridines in good yields. The reaction proceeded via initial Michael addition across the double bond followed by cyclization. The reaction of enaminone with aromatic aldehyde in acetic acid/ammonium acetate afforded the dihydropyridine that was oxidized to the corresponding pyridine.
α,β-Unsaturated nitriles are versatile reagents and their chemistry has received considerable attention. The reactivity of cinnamonitriles I toward active methylene reagents has been extensively utilised for synthesis of pyranes.
-OXOANILIDE AS BUILDING BLOCKS IN HETEROCYCLIC SYNTHESIS: A NEW SYNTHESIS OF POLYFUNCTIONALLY SUBSTITUTED PYRIDINES, PYRANS AND PYRIMIDINES