Multi-component solvent-free cascade reaction of 2-cyanoacetamides with ketones and acetone: highly regioselective synthesis of functionalized pyridin-2-ones bearing quaternary centers
A novel protocol has been constructed for the synthesis of four types of pyridin-2-ones (2−5) via a solvent-free cascade reaction of 2-cyanoacetamides 1, various ketones, and acetone via multicomponent reactions to prepare target compounds with good to excellent yields. As a result, functionalized pyridin-2-ones bearing quaternary centers (2-5), specifically, spiro pyridine-2-ones (3 and 5), which are promoted by piperdine under solvent-free conditions. Also, a double bond has been introduced into target compounds 4 and 5 only through the aryl substituted 2-cyanoacetamides under the same conditions. The advantages of this approach include no solvents, simple and practical operation (multi-component one-pot), high yields (up to 95%), and a product with potential biological activity.