Six-membered nitrogen-containing heterocycles are common skeletons in many natural products and exhibit diverse and important biological properties. 1 and 2 Alkaloids that contain the piperidine ring are targets for medicinal chemistry. 3, 4, 5, 6 and 7 Accordingly, functionalized δ-lactams have been generally used as precursors of the corresponding piperidines. 8, 9 and 10 Functionalized δ-lactams and structurally related compounds have attracted considerable attention ...