Homocoupling reactions alkynes, Sonogashira reaction

Suzuki-Miyaura as well as moderate activity in the Stille reaction ([M] = SnRa) were observed. In contrast to bis(NHC) complexes, inactivity in the Sonogashira reaction was due to increased activity in the homocoupling of alkynes [Eq. (47)], an undesired side reaction. 

However, the use of basic anions is not the sole approach followed to obtaining basic ILs. Liquid salts bearing this additional property can be prepared also by incorporation of a basic center into the cation. This approach generally affords more thermally stable ILs than those based on basic anions, which frequently present relatively low decomposition temperatures. Basic ionic liquids bearing aliphatic or aromatic amines on the side chain(s) have been synthesized and, recently, some of these have been used as both the solvent and base for Heck, copper free Sonogashira, and for homocoupling reactions of terminal alkynes (Figure 4.2). 

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