C–C Bond Forming Reactions Enabled by Vitamin B<sub>12</sub>─Opportunities and Challenges
Tomasz Wdowik, Dorota Gryko
Abstract
Cobalt not only is an essential micronutrient for mammals but also marks itself as important in organic synthesis, especially in the field of catalysis. Various useful reactions, such as alkene hydroformylation, hydrogenation, heterofunctionalizations of carbon–carbon double bonds, C–H activation, and cross-coupling reactions, have been realized with the aid of this metal. At the same time, cobalt deserves special attention as a catalyst for radical processes; in fact, in the form of vitamin B12, it was designed by Nature as a reversible carrier for radicals. Since this molecule is a native Co-complex, it is very attractive for the development of sustainable transformations, and it has already been demonstrated that vitamin B12 and its derivatives mediate numerous reactions that have found applications in both the construction of complex molecules and the degradation of polyhalogenated pollutants. However, in this Perspective, we focus the readers’ attention on radical C–C bond forming reactions catalyzed by vitamin B12, which are particularly important as a tool for the synthesis of important molecules in a greener manner. We also ponder over the challenges that remain to be addressed and the solutions that are expected to come.