developed for the synthesis of diversely functionalized dihydro-2-oxypyrroles and tetrahydropyridines. One-pot four-component reaction of dialkyl acetylenedicarboxylates, amines and formaldehyde in the presence of 2,6-pyridinedicarboxylic acid in methanol at room temperature provides dihydro-2-oxypyrroles. The combination of β-ketoesters, aromatic aldehydes and amines yielded tetrahydropyridine derivatives