BiREDOX · Bi(III)/Bi(V) Redox Catalysis for Organic Synthesis

Bi(III)/Bi(V) Redox Catalysis for Organic Synthesis

The continued use of non-earth abundant metals as catalysts represents a major challenge that must be addressed if truly sustainable processes are to be developed. In this regard, the development of new low-cost and non-toxic catalysts would be highly desirable with a significant impact to the environment and ultimately, our society. To this end, bismuth (Bi) represents an attractive alternative for the development of catalytic alternatives that secure sustainable and environmentally friendly approaches for organic synthesis. Interestingly, Bi is non-toxic in nature and has found application in the treatment of gastrointestinal disorders, Helicobacter pylori eradication and antitumoral studies. On the other hand, in the field of organic synthesis, Bi salts have been used in limited areas restricted to Lewis acid-catalysis, arylation and oxidation of alcohols. Despite the wide range of Bi salts capable of performing organic transformations, the ability to engage Bi(III) salts in catalytic redox processes is largely unknown. Hence, the major reason for this underdevelopment is the requirement of strong oxidants to achieve a higher oxidation state at the metal center, rendering an unfeasible catalytic cycle. Thus, BiREDOX aims at the rational design of novel Bi complexes to be engaged in catalytic Bi(III)/Bi(V) redox processes, which will represent an unprecedented strategy for organic synthesis, providing a greener and unique alternative to noble metals and contributing to achieving the Europe 2020 strategy priorities: sustainable growth and resource efficiency. The action achieved its main objectives, namely develop catalytic redox cycles based on the Bi(III)/Bi(V) redox pair. On one hand, a fluorination reaction of aryl boronic esters was developed, mimicking transition metal behavior and providing an alternative to the traditional methods reported with elements from the d-block. On the other hand, an unprecedented formation of carbon-triflate and carbon-nonaflate bonds was reported, showing how high-valent Bi catalysis can overcome some limitations of transition-metal-catalyzed processes and even be able to perform reactivity beyond them. Overall, the success of this MSCAction provides new catalytic alternatives utilizing an abundant and sustainable main group element, bismuth, opening new horizons and showing how main group elements can mimic fundamental organometallic steps traditionally performed by metals in catalysis.

Data: CORDIS, © European Union