New reactions of (vinylimino)phosphoranes with aldehydes involving an initial nucleophilic attack of the beta-carbon atom of the vinyl sidechain on the carbonyl carbon atom are reported. Iminophosphorane 4 derived from ethyl beta-azidoacrylate reacts with substituted cinnamyl aldehydes to give a mixture of 2-arylpyridine and 4-styryldihydropyridine derivatives, whereas the reaction with substituted