THE PREPARATION, PROPERTIES, AND STRUCTURE OF 2,6-BIS-(ALKYLAMINO)-2,5-HEPTADIEN-4-ONES

Abstract

2,6-Bis-(alkylamino)-2,5-heptadien-4-ones have been prepared by the action of aqueous amines on (1) 3-acetyl-4-hydroxy-6-methyl-2-pyrone (dehydroacetic acid), (2) 3-(1-alkylimino-ethyl)-4-hydroxy-6-methyl-2-pyrone, (3) 3-carboxy-2,6-dimethyl-4-pyrone, (4) 2,6-dimethyl-4-pyrone, (5) 2,6-dihydroxy-2,5-heptadien-4-one. The reactions are facile and proceed smoothly at temperatures near, or slightly above, room temperature. In (1) the first products are 3-(1-alkyliminoethyl)-4-hydroxy-6-methyl-2-pyrones, followed by the 2,6-bis-(alkylamino)-2,5-heptadien-4-one. The other reactions yield only the latter product, but in all cases it decomposes to the 4-pyridone at higher temperature, or on prolonged reaction or by the action of acid.The 2,6-bis-(alkylamino)-2,5-heptadien-4-ones are pale yellow compounds with a slight violet fluorescence. Infrared, n.m.r., and ultraviolet spectra are consistent with an open-chain, internally hydrogen-bonded structure.