Studies on Ketene and Its Derivatives. XXXII. Reactions of α, β-Unsaturated Acid Anhydride with β-Aminocrotonamide and Related Compounds

Abstract

Acylation of β-aminocrotonamide (I) with α, β-unsaturated acid anhydride (e. g. acrylic, crotonic and methacrylic anhydrides) afforded 2-methyl-6-oxo-1, 4, 5, 6-tetrahydro-pyridine-3-carboxamide derivatives (IV), which were easily dehydrogenated by heating with Pd-black to give 2-methyl-6-oxo-1, 6-dihydropyridine-3-carboxamides. Similarly, acylation of primary enamines such as ethyl β-aminocrotonate (XIa), 4-amino-3-penten-2-on (XIb), 2-amino-1-propenyl phenyl ketone (XIc), and 2-aminocrotononitrile (XId) with acrylic anhydride afforded 5-substituted-6-methyl-3, 4-dihydro-2-pyridones (XII), which were given by the reaction of the primary enamines (XI) with ethyl acrylate in the presence of sodium ethoxide.