Abstract
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Cycloaddition of acetylbenzoyl ketene generated in situ as an intermediate during one‐step reaction between excess benzoylacetone and oxalylchloride to C=C double bond of cyclic enol form of benzoylacetone gave 3‐acetyl‐5‐benzoyl‐6‐methyl‐2‐phenyl‐4(4__H__)‐pyrone 1a. Condensation reactions of 1a together with 3,5‐dibenzoyl‐2,6‐diphenyl‐4(4__H__)‐pyrone 1b and 3‐benzoyl‐5‐ethoxycarbonyl‐2,6‐diphenyl‐4(4__H__)‐pyrone 1c with two‐fold excess primary amines provided a series of 3‐benzoyl‐1‐alkyl‐5‐(1‐alkylimino‐ethyl)‐6‐phenyl‐2‐methyl‐4(1__H__)‐pyridinone 2, 3,5‐dibenzoyl‐1‐alkyl‐2,6‐diphenyl‐4(1__H__)‐pyridinone 3a‐c and 3‐benzoyl‐1‐alkyl‐5‐ethoxycarbonyl‐2,6‐diphenyl‐4(1__H__)‐pyridinone 3d,e derivatives, respectively. In addition, while prolonged reaction of n‐pentylamine with unsymmetrical pyrone derivative 1a gives a symmetrical pyridinone derivative namely 3,5‐dibenzoyl‐2,6‐dimethyl‐1‐pentyl‐4(1__H__)‐pyridinone 5, much prolonged action n‐pentylamine and then aqueous n‐pentylamine on 1b resulted in degradation of the 4‐pyrone ring to give dibenzoylmethane.