An efficient method for the construction of polysubstituted 4-pyridones via self-condensation of β-keto amides mediated by P2O5 and catalyzed by zinc bromide

• Main Authors: Liquan Tan, Peng Zhou, Cui Chen, Weibing Liu
• Format: Article
• Language: English
• Published: Beilstein-Institut 2013-11-01
• Series: Beilstein Journal of Organic Chemistry
• Subjects: β-keto amide; phosphorus pentoxide; 2-pyridones; 4-pyridones; self-condensation
• Online Access: https://doi.org/10.3762/bjoc.9.304

A self-condensation cyclization reaction mediated by phosphorus pentoxide (P2O5) and catalyzed by zinc bromide (ZnBr2) is presented for the synthesis of polysubstituted 4-pyridones and 2-pyridones from β-keto amides. A variety of β-keto amides are used in this approach, and a wide range of functionalized 4-pyridones and 2-pyridones were obtained in good to excellent yields. When employing the N-aryl β-keto amides as the substrates in this protocol, 4-pyridones are resulted, however, when using N-aliphatic-substituted β-keto amides as the partners of N-aryl β-keto amides under the same conditions, 2-pyridones are afforded.