Molten salts (ionic liquids) to improve the activity, selectivity and stability of the palladium catalysed Trost-Tsuji C-C coupling in biphasic media

The Trost-Tsuji C-C coupling between ethyl cinnamyl carbonate and ethyl ace toacetate catalysed by a water soluble Pd/TPPTS catalyst (TPPTS = triphenyl phosphine trisulphonate, sodium salt) and possible side reactions have been investigated in several biphasic media at 60-80 degrees C. The use of the ionic liquid 1-butyl-3-methylimidazolium chloride as the catalytic layer br ings definitive advantages over an aqueous catalytic phase: Palladium chlor ide may be used as the catalyst precursor, the solubility of the organic re agents is much higher which leads to faster reaction rates, the formation o f cinnamyl alcohol is suppressed and common organic layers such as alkanes can be used with no noticeable catalyst deactivation. The yields in the C-C product up to 90% with TOF number, of 23 h(-1) may, thus, be achieved. (C) 1999 Elsevier Science B.V. All rights reserved.