Solvent Dependent Preparation of CuI Nanocrystals and the Catalysis in Sonogashira Coupling Reaction

Abstract

Octahedral and rod-like γ-CuI nanocrystals have been fabricated by using a mild solution method in water, methanol and ethanol respectively. X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) were used to characterize the product. The as-synthesized CuI demonstrates higher activity for the Sonogashira cross-coupling of 4-iodoanisole and phenylacetylene.

Solvent effects in palladium catalysed cross-coupling reactions

“…Polyethylene glycol (PEG) is an alternative cross-coupling medium, as demonstrated for Stille, Suzuki, and Heck reactions, 302 and Sonogashira reactions. 303 A variety of relatively low molecular weight PEG oligomers are applicable as a solvent for cross-coupling reactions, and the higher molecular weight polymers can be used as additives and catalyst supports. 304,305 When Nobre et al used a mixed PEG-methanol reaction solvent for Suzuki reactions, immiscible non-polar solvents could be used to extract the product, avoiding an aqueous-organic separation.…”

Sonogashira Reactions Using Nanocatalysts

“…121 An example of coupling of an aryl chloride is shown in Scheme 4.21, where the electron-deficient 1-chloro-4-nitrobenzene is cross-coupled with phenylacetylene to give alkyne 60. In addition, octahedral and rod-like ␥ -CuI nanocrystals were used as catalysts (10 mol%), combined to triphenylphosphane in the presence of potassium carbonate, in the cross-coupling reaction of 4-iodoanisole and phenylacetylene performed in PEG-400 as solvent at 130 • C. 122 Moreover, commercial CuO nanoparticles have been employed as catalysts in the Sonogashira coupling of aryl iodides with terminal alkynes, using potassium carbonate as base in DMSO as solvent at 160 • C. 123 However, the catalyst was not reusable as TEM analysis showed that most of the CuO nanoparticles were aggregated after the reaction. Interestingly, other nanometal oxides such as nano-Fe 2 O 3 , nano-NiO, and nano-In 2 O 3 produced only trace amounts of the Sonogashira product under the same reaction conditions.…”

N,N-Dimethylformamide-stabilized copper nanoparticles as a catalyst precursor for Sonogashira–Hagihara cross coupling

“…M NPs stabilized by dendrimers and supported on metal oxides have also been reported. [26][27][28][29] Copper NPs (Cu NPs) with various nanostructures have also been developed, and research into their applicability as catalysts has been carried out. 26,27,30 There are many reports of Sonogashira coupling catalyzed by M NPs.…”

“…[34][35][36][37] In addition, a greater amount of catalyst is required for Cu NP-catalyzed reactions, and multi-step procedures are required for the synthesis of these catalysts. 28,29,[34][35][36][37] Rothenberg and co-workers were the rst to report a coppercatalyzed palladium-free and ligand-free Sonogashira cross coupling with various aryl iodides and bromides. 35 For this they used Cu nanoclusters prepared from chloride salt precursors by using tetra-n-octylammonium formate (TOAF) as a stabilizer in DMF at 65 C. However, a multi-step operation was required for the synthesis of the Cu nanoparticles and the Sonogashira reaction was carried out with 5 mol% of the Cu NP catalyst.…”