Sustainable steps forward in vitamin B12-catalysis.

Vitamin B12, a naturally occurring cobalt complex, plays a vital role as a cofactor in biological processes for adenosylcobalamin- and methylcobalamin-dependent enzymes, where it is essential in DNA synthesis, neurological function, or red blood cell formation. Beyond its biological significance, vitamin B12 exhibits unique reactivity: in the presence of suitable reagents, it forms Co-alkyl complexes that, under light irradiation or thermal activation, generate C-centered radicals that engage in reactions with various SOMOphiles and electrophiles. The feature review highlights catalytic properties of this native cobalt-complex, with particular emphasis on emerging strategies that address the growing demand for more sustainable chemical processes. Remaining challenges and potential future directions are also discussed.