Ionic liquids, that is molten salts, may represent activating and stabilizing solvents for C-C coupling reactions. In particular, tetrabutylammonium bromide (TBAB) is particularly suitable for Heck reactions as it enhances reaction rates. In the presence of tetrabutylammonium acetate as base, palladium complex with benzothiazolidene as ligands as well palladium acetate are transformed to Pd-nanoparticles which allow regio- and stereo-specific Heck reactions with very high TON and TOE Beside this, TBAB enhances, by solvation, the formation and reactivity of carbanions. A comparative study on effects exerted by different ionic liquids on catalyst stabilization, reaction rates and regio- and stereo- selectivity in the C-C coupling reactions is also reported. (C) 2004 Elsevier B.V. All rights reserved.