A Hantzsch Amido Dihydropyridine as a Transfer Hydrogenation Reagent for α,β-Unsaturated Ketones

An improved synthesis of the bis-methylamido Hantzsch dihydropyridine is described. The Hantzsch amide is demonstrated to be an effective transfer hydrogenation reagent using alpha,beta-unsaturated ketones as the test case. Unreacted Hantzsch amide and the bis-methylamidopyridine byproduct are effectively removed by extraction in contrast to the commonly used Hantzsch diethyl ester. Several examples are given with the reaction being more effective for conjugated aromatic substrates than for aliphatics.