A “one pot” synthesis of polysubstituted pyridines from metallated alkylphosphonates, nitriles and α,β-unsaturated ketones

A simple and efficient synthesis of polysubstituted pyridines is described. The key step is based on the regioselective addition of lithiated β-enaminophosphonates 5 to unsaturated carbonyl compounds 3. Pyridines 1 can also be obtained in “one pot” reaction from phosphonates 6 when these compounds are metallated followed by addition of nitriles and unsaturated carbonyl compounds.