A highly efficient access to enantiopure tetrahydropyridines: dual-organocatalyst-promoted asymmetric cascade reaction

A highly efficient cascade process of Michael-aza-Henry-hemiaminalization-dehydration was established for the construction of enantiopure tetrahydropyridines using the combination of prolinol trimethylsilyl ether and cinchona alkaloid catalysts. This new approach allowed for the application of aliphatic imines, generated in situ from aldehydes and amines. Good yields (up to 90%), high enantio- (up to >99% ee) and diastereoselectivities (>99: 1 d.r. in all cases) were achieved for a broad spectrum of substrates under mild conditions.