Iron-Catalyzed Arene Prenylation

The syntheses of prenylated arenes and 2,2-dimethylchromans using a Friedel-Crafts-type coupling between activated arenes and isoprene is reported. A combination of catalytic amounts of FeCl3 and AgBF4 promotes a regioselective prenylation event followed by a cyclization to form a 2,2-dimethylchroman structure. The method avoids isoprene polymerization and allows the facile late-stage derivatization of biologically active motifs.