“Fluoroalkylative olefin difunctionalization by highly reducing organic photoredox catalysts”
Munetaka Akita Laboratory for chemistry and life science, Tokyo Institute of Technology
Photoredox catalysis is an efficient method for generation of radical species under mild reaction conditions. Radicals can be generated via either 1e-reduction of electron-deficient precursors or 1e-oxidation of electron-rich precursors. As the catalysts, those containing rare elements (e.g. Ru, Ir) have been used but, taking into account the scarcity of the elements, it is desirable to replace them by organic catalysts. While, for the oxidation processes, mesitylacrdinium salt developed by Fukuzumi is now widely used, highly reducing organic catalysts are demanded. Fluoroalkyl groups (Rf) groups are regarded as versatile structural motifs, especially in the fields of pharmaceuticals and agrochemicals, and development of simple methodologies for efficient and selective incorporation thereof into various organic skeletons is also demanded. We have been studying fluoroalkylation with electron-deficient precursors, which require highly reducing catalysts, in particular, for precursors with a lesser number of fluorine atoms (e.g. CF2H, CFH2). We have revealed that simple polyaromatic hydrocarbon (PAH) catalysts such as perylene and bis(diarylamino)-anthathene and -naphthalene promote fluoroalkylative difunctionalization of unsaturated hydrocarbons. Despite the very short ns-order lifetime of the photo-excited organic catalysts, they show performance much better than [fac-Ir(ppy)3] known so far as the strongest reducing catalyst.