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

Liquan Tan,Weibing Liu,Peng Zhou,Cui Chen

doi:10.3762/bjoc.9.304

Abstract

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.

Highlights

Introduction βKeto amide and their derivatives are desired classes of intermediates for the synthesis of nitrogen- and oxygen-containing heterocyclic compounds since they possess six reactive sites in the same molecule (Scheme 1) [1,2,3,4,5,6,7]
A lot of reports can be found in the literature concerning the construction of different heterocyclic compounds from β-keto amides by modification of the six different reactive positions [8,9,10,11,12,13]
We report an improved efficient method for the construction of polysubstituted 4-pyridones and 2-pyridones via phosphorus

Summary

Introduction

Introduction βKeto amide and their derivatives are desired classes of intermediates for the synthesis of nitrogen- and oxygen-containing heterocyclic compounds since they possess six reactive sites in the same molecule (Scheme 1) [1,2,3,4,5,6,7]. Two groups reported the self-condensation of N-aryl β-keto amides. Scheme 1: The six different reactive positions of β-keto amides.

Results

Conclusion