Redox Catalysis for Sustainable Radical Synthesis – Credox

Over the last three decades, the radical chemistry has witnessed tremendous developments. Its contribution has greatly extended the repertoire of versatile processes in organic synthesis. One of the main achievements of radical chemistry is the design of polycyclization cascades that could lead to natural products, as well as the preparation of enantiopure substrates thanks to highly controlled asymmetric processes. However, radical reactions suffer from the difficulty in scaling up and have relied on the use of toxic mediators that cause environmental issues. In this project, we are aiming at the development of new single electron transfer (SET) processes which would transform charged or uncharged species into radical entities. In the first phases of the program, we will turn our attention to redox processes which involve stoichiometric amounts of reducing or oxidizing agent. These agents can be transition metal salts Fe (III), Cu(II), Ce(IV), Ti(III) or Sm(II), but also organic mediators such as hypervalent iodine species. We will initially study the reduction of onium species in order to master the scope of the homolytic processes and also propose a new general method for the formation of radicals. We will study the oxidation of boron and aluminium ate complexes as well as hypervalent silicon species. A special attention will be directed toward the generation of phosphorus centered radicals which should find interest in biological studies. In a second phase, which corresponds to Task 2, we will examine all these reactivities focussing on catalytic versions. For that purpose, we will study oxidative and reductive photocatalysis reactions with ruthenium or iridium complexes for which redox properties are altered with visible light. Task 3 will consist in the application of the obtained results in the 2 first phases in novel radical cascades involving cyanamides and which should allow the formation of phospho- or thioamidines for uses in organometallic catalysis and organocatalysis respectively. Thus, in the context of a high-performance and modern organic chemistry, the molecular chemist has to explore any mild and selective mode of activation in order to propose new synthetic methods. Moreover, the development of a more ecocompatible processes has imposed as a goal of utmost importance.