Vitamin B₁₂ in Photocatalysis – An Underexplored Frontier in Cooperative Catalysis

Abstract

Vitamin B12 (VB12) is a flexible and sustainable catalyst both in nature and the reaction flask, facilitating varied organic transformations of high value to both enzymatic processes and synthetic chemists. Key to this value is the breadth of reactivity it possesses, capable of both ionic, 2 electron chemistry, and radical, 1 electron chemistry. In particular, the ability to generate carbon‐centered radical intermediates via photolysis of organocobalt intermediates formed from alkyl electrophiles opens the door to powerful new radical transformations challenging to achieve using classical photoredox or ligand‐to‐metal charge transfer (LMCT) catalysis. While this unique photocatalytic reactivity of VB12 has been increasingly leveraged in monocatalytic schemes, recent reports have demonstrated VB12 is able to function as a powerful photocatalyst in cooperative schemes, driving diverse reactivity including remote elimination of alkyl halides, regioselective epoxide arylation, and regioselective epoxide reduction. This concept briefly overviews the enabling properties of VB12 as a photocatalyst and recent applications in cooperative catalysis, providing a framework for the continued development of new cooperative catalyst systems using this powerful photoactive complex.

Trans influence of cyanide on the structural and electronic properties of a series of organocobaltIII(TIM) complexes

“…3,4 Creative applications of vitamin B 12 in cooperative photocatalytic systems have achieved even more diverse reactivities, including regioselective epoxide arylation and reduction. 5…”