A study by Gallagher and Maleczka has shown that the use of PMHS, CsF, CuX and a palladium catalyst facilitates Sonogashira coupling under mild, relatively neutral, amine-free conditions. All 4 reagents were essential for Sonogashira coupling to occur. Catalytic amounts of copper thiophenecarboxylate (CuTC) or CuCl can be used provided the alkyne is coupled with a triflate or nonaflate. Bromides or chlorides react, but only when stoichiometric quantities of CuTC or CuCl are present. In a typical reaction an alkyne is reacted with 1.5 equivalents of nonaflate or triflate, PMHS (2 equiv), CsF (5 equiv), CuCl or CuTC (5 mol%) and bistriphenylphosphine palladium dichloride (5 mol%). Yields are mainly 80-96% with one or two exceptions. When compared with traditional Sonogashira conditions the PMHS version gives superior results with no homocoupled dialkynes being formed. (Synlett 2003, (4), 537-541).