Vitamin B₁₂ is a highly functionalized tetrapyrrolic compound bearing a central cobalt ion. It has been examined as an oral delivery vehicle for therapeutic agents, as an artificial enzyme and more importantly as a catalyst for various organic reactions.^{[1], [2]} Like most great ideas vitamin B₁₂ catalysis was inspired by the ultimate chemist Nature, as methylcobalamin and adenosylcobalamin are involved in numerous biocatalytic reactions including isomerization, methylation and dehalogenation.^[2] This type of catalysis has been successfully translated into the laboratory and used in a small collection of reactions.^[3] The advantage of using vitamin B₁₂ lays in the complete stability of the central cobalt ion, whereas most catalytic reactions require the addition of toxic metals plus complex ligands into a cocktail of reagents, vitamin B₁₂ in itself is a package deal. Furthermore, it has been well documented that the reaction mechanism usually follows a radical pathway, bringing a new dimension to this already interesting field.

We have shown that vitamin B₁₂ is an effective catalyst for not only C-C bond forming reaction but also cleavage of C-O bonds under light irradiation.

Reference:

1.     Banerjee, R. Chemistry and Biochemistry of B₁₂, John Wiley & Sons, Inc, 1999

2.     K. ó Proinsias, M. Giedyk, D. Gryko, Chem. Soc. Rev. 2013, 42, 6605-6619.

3.  Giedyk, M.; Fedosov, S.; Gryko, D. Chem. Commun. 2014, 50, 4674-4676.

4. a) Shimakoshi, H.; Nishi, M.; Tanaka, A.; Chikama, K.; Hiseada, Y. Chem. Commun. 2011, 47, 6548-6550. b) K. Tahara, Y. Hisaeda, Green Chem. 2011, 13, 558-561. H. Shimakoshi, L. Li, M. Nishi, Y. Hisaeda, Chem. Commun. 2011, 47, 10921-10923.