Green synthesis of liquid crystal intermediates the preparation of phenylacetylenes in ionic liquids

Sonogashira coupling of phenylacetylenes with phenyl iodides in 1-butyl-3-methylimidazolium bromide (BMImBr) was explored. Using CuI/Pd(PPh3)(4) as a catalyst and Im as the base, the expected substituted acetylenes were obtained with good to excellent yields (61%-95%) under mild conditions (4h, 60 degrees C). After the product was isolated, the left ionic liquid can been readily recovered and reused in the subsquent runs with almost the same efficiency. The reactivity of different iodoarenes with terminal alkynes was also discussed.