Advanced flavin catalysts elaborated with polymers

A variety of biological redox reactions are mediated by flavoenzymes due to the unique redox activity of isoalloxazine ring systems, which are found in flavin cofactors. In the field of synthetic organic chemistry, the term “flavin” is generally used for not only isoalloxazines but also related molecules including their isomers and some analogues, and those having catalytic activity are called flavin catalyst. Flavin catalysts are typically metal-free, and their catalytic activity can be readily accessed using mild terminal oxidants such as H2O2 and O2; therefore, redox reactions with these compounds have great promise as alternatives to reactions with conventional metal catalysts for the sustainable production of important chemicals. We recently became interested in using polymers for the development of flavin catalysts, especially to improve their practicality and advance the field of catalysis. Here, we summarize our recent research on such flavin-polymer collaborations including the development of facile preparation methods for flavin catalysts using polymers, readily reusable polymer-supported flavin catalysts, and flavin-peptide-polymer hybrids that can catalyze the first flavoenzyme-mimetic aerobic oxygenation reactions

sp3 C–H Bond Functionalization with Ruthenium Catalysts

International audienceThe selective formation of carbon–carbon bond by functionalization of an sp3C–H bond is still a challenge in organic synthesis. There are already examples involving transition metal catalysis. In this chapter we review the use of ruthenium(0) and ruthenium(II) catalysts for the formation of carbon–carbon bonds based on creation of reactive sites by sp3C–H bond activation. We show that in most cases, regioselective sp3C–H bond activation is induced either from functional substrates bearing a directing group, which strongly coordinates the metal centre, or by selective C–H bond activation at the α-carbon of a heteroatom accompanied by hydrogen transfer processes and transient creation of reactive functional group