Rare earth(III) perfluorooctane sulfonates and perfluorooctanesulfonic acid in fluorous solvents: Novel and recyclable catalytic systems for Friedel-Crafts acylation of unactivated benzenes

Catalytic Friedel-Crafts acylation of benzene and unactivated benzenes, such as chlorobenzene and fluorobenzene, was successfully accomplished using rare earth(III) perfluorooctane sulfonates (RE(OPF)(3)), RE = Sc, Y, La similar to Lu) and perfluorooctanesulfonic acid (PfOH) as catalysts in fluorous solvents. Solutions of Yb(OPf)(3) and PfOH in perfluorodecalin (C10F18, cis and trans-mixture) are the most suitable catalytic system, with catalyst loading as low as 0.4%mol leading to clean, high-yielding benzoylation of a variety of unactivated benzenes. By simple separation of the fluorous phase containing only catalyst, acylation can be repeated several times. (c) 2005 Elsevier B.V. All rights reserved.