An efficient protocol for copper-free palladium-catalyzed Sonogashira cross-coupling in aqueous media at low temperatures

A thorough study on copper-free Sonogashira cross-couplings in water was carried out using the palladacycle, [{Pd(mu-Cl){kappa(2)-P,C-P(Pr-i)(2)(OC6H3-2-Ph)}}(2)] as pre-catalyst with different bases and palladium concentrations. The highly active pre-catalyst imparts good to near quantitative yields using a concentration of 0.25 mol % at 40 degrees C. This broadly applicable protocol exhibits high tolerance of functional groups and substitution patterns. (C) 2011 Elsevier Ltd. All rights reserved.