Antivitamins B 12 —Some Inaugural Milestones

The recently delineated structure‐ and reactivity‐based concept of antivitamins B 12 has begun to bear fruit by the generation, and study, of a range of such B 12 ‐dummies, either vitamin B 12 ‐derived, or transition metal analogues that also represent potential antivitamins B 12 or specific B 12 ‐antimetabolites. As reviewed here, this has opened up new research avenues in organometallic B 12 ‐chemistry and bioinorganic coordination chemistry. Exploratory studies with antivitamins B 12 have, furthermore, revealed some of their potential, as pharmacologically interesting compounds, for inducing B 12 ‐deficiency in a range of organisms, from hospital resistant bacteria to laboratory mice. The derived capacity of antivitamins B 12 to induce functional B 12 ‐deficiency in mammalian cells and organs also suggest their valuable potential as growth inhibitors of cancerous human and animal cells.