An Efficient Synthesis of Functionalized 2-Pyridones by Direct Route or via Amide/Enolate Ammonium Salt Intermediates

Abstract

A number of compounds with a 2-pyridone structure 3, which have different substituents and are analogous to cardiotonic drugs like milrinone, have been synthesized in high yields from the appropriate enamino ketones 2 using different cyanomethylene active compounds (methyl cyanoacetate, benzoylacetonitrile and phenylsulfonylacetonitrile). In this synthetic route, the active role of the dimethylamine released in situ on the cyclization process has been underlined. In particular, its direct intervention, as a nucleophile or a base, was proven and intermediate amides 5 or enolate ammonium salts 6 were isolated and recognized by the analytical and spectral data.

N-Sulfonylbenzotriazoles as Advantageous Reagents for C-Sulfonylation

“…Synthesis of α -Cyanoalkyl Sulfones. α-Cyanoalkyl sulfones have extensive synthetic uses, e.g., for the preparation of pyridones, 4-aminopyrimidines, 5,6-dihydro-4 H -pyrans, tetrahydrofurans, cyclobutanes, cyclopropanes, and biologically active compounds such as β -amido sulfones and l -indospicines …”

An Efficient Approach to 3,4-Disubstituted Pyridin-2-ones. Formal Synthesis of Mappicine Ketone

“…Six-membered nitrogen containing heterocycles has been intensively studied in the synthesis of alkaloids, and a great number of them have significant biological activities. , It is well-known that the pyridin-2-one ring system is a valuable building block in natural product synthesis . Numerous methods for the preparation of substituted pyridin-2-one had been reported in the literature …”