2-Amino-4-(alkoxymethyl)-1,3-butadienes react smoothly with nonactivated aldimines derived from aromatic aldehydes in the presence of ZnCl2 as Lewis acid giving rise, with good yields and very high stereoselectivity, to substituted 4-aminotetrahydropyridines which upon hydrolysis yield 4-piperidone derivatives. Moreover, the stereochemistry of the cyclization process depends on the nature of the N-substituent of the imine.