Multicomponent synthesis of substituted pyridines via a catalytic intermolecular aza-Wittig/Diels-Alder sequence.

A three-component synthesis of polysubstituted pyridines has been developed, based upon the synthesis of 2-azadienes by a redox-neutral catalytic intermolecular aza-Wittig reaction and their subsequent Diels-Alder reactions. The two-pot process has been demonstrated using a range of aryl and heteroaromatic aldehydes, substituted α,β-unsaturated acids and push-pull enamines, to give rapid access to diverse tri- and tetrasubstituted pyridines.