Abstract:
The Michael–Mannich–cyclization cascade of dicyano olefins, 1-(2-alkoxy-2-oxoethyl)pyridin-1-ium halogenides, aromatic aldehydes and ammonium acetate provides convenient stereoselective formation of (4,6-diaryl-5,5-dicyano-2-oxo-piperidin-3-yl)pyridin-1-ium halogenides with three stereogenic centres. Ammonium acetate plays dual role acting as a base and as a nitrogen source.