Graphical Abstract
The transmetalation of a vitamin B12 building block was achieved as follows: oxidation of 1, NCo(CN)2, to the seco compound, demetalation, reaction with Ni(ClO4)2, and recyclization at 100°C to give 1, MNiClO4. Corrinoids of this kind, containing metal ions other than cobalt, were previously only accessible from natural metal-free corrinods or by total synthesis.