Publication Details (including relevant citation information):
Dmitry Tsvelikhovsky[a] and Jochanan Blum*[a]
Eur. J. Org. Chem. 2008, 2417–2422
Institute of Chemistry, Hebrew University, Jerusalem 91904, Israel Fax: +972-2-6513832 email@example.com
Heck, Stille, Suzuki and three-component coupling reactions with hydrophobic substrates have been carried out in water. The substrates are initially transformed by a general pro- cedure into a microemulsion, which consists of nearly 90% water with the aid of sodium dodecyl sulfate and either PrOH or BuOH. The surfactant carries the molecules of the sub- strates to Pd(OAc)2 entrapped within a hydrophobicitized sil- ica sol–gel matrix where the coupling between the substrates is assumed to take place. The products are then returned by the surfactant into the microemulsion from which it can be released. The immobilized palladium catalyst is leach proof and recyclable. It can be used in various coupling processes at least six times without loss of activity. Experiments with D2O have revealed that the water does not take part in the coupling process, but it has an effect on the pore size of the sol–gel matrix, which hosts the palladium catalyst.