Stereoselective Synthesis of 4-Piperidone and 4-Aminotetrahydropyridine Derivatives by the Imino Diels-Alder Reaction of 2-Amino-1,3-butadienes

Article abstract of DOI:10.1021/jo00064a030

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-substitutent of the imine.