gamma-Arylated gamma,delta-unsaturated ketones have been prepared in good to excellent yields via the Pd-catalyzed Heck arylation of an electron-rich olefin, 5-hexen-2-one (1), with aryl bromides (2a-21) in the ionic liquid [bmim][BF4]. The reaction is highly regioselective, leading predominantly to branched, gamma-arylated products with Pd-DPPP [DPPP = 1,3-bis(diphenylphosphino)propane] catalysis. However, the choice of ligand is found to be crucial for regiocontrol; a change of ligand from DPPP to 1,1'-bis(diphenylphosphino)ferrocene (DPPF) affords predominantly the (E)-type, delta-arylated gamma,delta-unsaturated ketones. The method is simple, effective, and applicable to the coupling of both electron-rich and electron-deficient aryl bromides with no need for any halide scavengers. (c) 2006 Elsevier B.V. All rights reserved.