Vitamins are organic molecules that are essential for the proper functioning of mammalian cells. Among them, there is only one organometallic molecule: vitamin B-12, a natural cobalt complex that is involved in DNA synthesis and regulation, the functioning of the nervous system, the formation of red blood cells, etc. Being a co- factor for enzymes dependent on adenosylcobalamin and methylcobalamin, vitamin B-12 plays a crucial role in isomerization, methyl transfer, and dehalogenation reactions. Its activity, however, is not limited to the reactions taking place under physiological settings. It has been widely explored as a preferable catalyst for sustainable organic synthesis, and an abundance of B-12-catalyzed strategies has already been developed. In this perspective, we highlight the underlying principles and catalytic propensity of vitamin B-12 in the generation of C-centered radicals from various precursors and their use in the synthesis of important molecular scaffolds. We also discuss challenges for future discoveries.
