Science of Synthesis

Griesbeck, A. G.; Soldevilla, A., Science of Synthesis, (2008) 43, 370.

Copper-free Sonogashira reactions can also be carried out in ionic liquids. This variation is advantageous in that the catalyst may be recycled, since the products are easily separated from the transition-metal catalysts dissolved in the ionic liquids by simple extraction with a conventional organic solvent. A typical example is shown in ‌Scheme 31‌, where 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) is used as the ionic liquid, dichlorobis(triphenylphosphine)palladium(II) as the catalyst, and diisopropylamine or piperidine as the base.[‌96‌,‌97‌] The reaction proceeds with good yields of products ‌57‌, in the absence of a copper cocatalyst, and has been also carried out in a microreactor.[‌96‌,‌97‌]

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References