Convenient palladium-catalyzed homocoupling of iodoarenes in an ionic liquid

Carboxylate‐Based, Room‐Temperature Ionic Liquids as Efficient Media for Palladium‐Catalyzed Homocoupling and Sonogashira–Hagihara Reactions of Aryl Halides

“…Benzyl-3-butylimidazolium tetrafluoroborate ([bmim]PF 6 ) has only been applied as a solvent in the tetrakis(dimethylamino)ethylene (TDAE)/Pd-promoted homocoupling reaction of iodoarenes. [22] An imidazolium-based phosphinite, which is liquid above 80°C, was also reported by our group as an efficient reagent system for homocoupling of aryl iodides and bromides. [23] Herein, we report on the successful application of a new class of easily prepared, carboxylate-based, room-temperature ILs for phosphane-and base-free homocoupling and also phosphane-and copper-free Sonagashira reactions of aryl iodides and bromides.…”

Versatile Synthesis of Pentalene Derivatives via the Pd-Catalyzed Homocoupling of Haloenynes

“…Recent reports have described the Pd-catalyzed homocoupling of aryl halides with reducing agents such as zinc, 22 indium, 23 hydrogen gas, 24 formate salts, 25 hydroquinone, 26 alcohols, 27 and amines. 28 Screening of various reaction conditions with such reductants revealed that the highest yields of dibenzopentalene (>80%) were obtained in the presence of 2 equiv of hydroquinone and Cs 2 CO 3 (entry 1, Table 1). Consistent with reports on Pd-catalyzed Ullmann couplings, 22,24,25,27 small amounts (typically <5%) of the hydrodehalogenated product were obtained as side products.…”

Ionic liquids: a versatile medium for palladium-catalyzed reactions

“…Functionalized symmetrical biaryls have been synthesized in good yields via TDAE/Pd-promoted homocoupling reaction of substituted iodoarenes using the ionic liquid, [bmim] [PF 6 ] (Scheme 47). 197 The catalytic system could be recycled and reused four times without any loss in the catalytic activity.…”