Formation of C–C, C–S and C–N bonds catalysed by supported copper nanoparticles

Abstract

a Transition-metal catalysed cross-coupling reactions are still dominated by palladium chemistry. Within the recent past, copper has gained ground against palladium by virtue of its cheaper price and equivalent function in certain reactions. Four catalysts consisting of copper nanoparticles on zeolite, titania, montmorillonite and activated carbon have been tested in three palladium-and ligand-free cross-coupling reactions to form carbon-carbon, carbon-sulfur and carbon-nitrogen bonds. CuNPs/zeolite has been found to be the best one in the Sonogashira reaction of aryl iodides and arylacetylenes, as well as in the coupling of aryl halides with aryl and alkyl thiols, being reusable in both cases. However, the arylation of nitrogencontaining heterocycles (imidazole, pyrazole, benzimidazole and indole) has been better accomplished with CuNPs/titania, albeit CuNPs/activated carbon showed better recycling properties. The catalytic activity of the nanostructured catalysts has been compared with that of twelve commercial copper catalysts, with the former outperforming the latter in the three types of reactions studied.

Abatement of the Stimulatory Effect of Copper Nanoparticles Supported on Titania on Ovarian Cell Functions by Some Plants and Phytochemicals

“…None of the plant additives promoted any CuNPs/TiO 2 effect, which might indicate that the tested plant additives could oppose the action of CuNPs/TiO 2 . Based on our experience on CuNPs [ 23 , 24 , 25 , 26 ], we know that their catalytic activity in chemical reactions can be depleted or even completely blocked by their interaction with hydroxyl groups present in organic molecules. Taking into account that plant extracts, as well as rutin and apigenin, are rich in hydroxyl groups, because of the presence of carbohydrate and/or phenolic units, their binding to the surface of the CuNPs could passivate it, with the concomitant reduction of CuNPs’ bioactivity.…”

“…We have been involved in the development of methods to prepare metal nanoparticles [ 21 ], copper nanoparticles among them [ 22 ], which have found application as chemical catalysts either unsupported [ 23 ] or supported on a variety of inorganic supports, including zeolite Y [ 24 ], charcoal [ 25 ], and titania [ 26 ]. A previous comparison of CuNPs of different size, morphology, and inorganic support enabled us [ 20 ] to identify CuNPs supported on titania nanopowder (CuNPs/TiO 2 ) as a nanoparticle combination with a potent direct effect on ovarian cells.…”

Synthesis of Dihydroindoloisoquinolines through Copper‐Catalyzed Cross‐Dehydrogenative Coupling of Tetrahydroisoquinolines and Nitroalkanes

“…(Nitromethyl)benzene did not react under thesec onditions. Unfortunately,c ontrary to previousw ork, [12] the catalyst could not be effectively recycled;t he conversion dropped to 50 %i nt he second run. We observed by X-ray photoelectron spectroscopy (XPS) the adsorption of nitrogen specieso nt he surfaceo ft he catalyst after reuse, which might causei ts passivation ( Figure S2 c, Supporting Information).…”

“…[10] In recent years, the synthesis and modification of nitrogen heterocycles through transition-metal-catalyzed sp 2 functionalizationh as attracted ag reat deal of attention. [11] As parto fo ur interest on the application of coppern anoparticles (CuNPs)i n coupling reactions, [12] here, we want to put forward the unparalleled reaction of tetrahydroisoquinolines and nitro compounds leading to 5,6-dihydroindolo[2,1-a]isoquinolines catalyzed by supported CuNPs throughC DC under aerobic conditions [13] (Scheme 1c). We first optimized the catalytic system and reaction conditions using N-phenyl-1,2,3,4-tetrahydroisoquinoline (2a)a nd nitroethane (3a)a sm odel substrates (Table 1).…”

Earth-Abundant d-Block Metal Nanocatalysis for Coupling Reactions in Polyols

“…Gaining a better understanding on the physicochemical processes leading to the formation of MNPs is key for the design of nanocatalysts with defined morphology[50,96], notably when catalyst heterogenization with solid supports such as zeolites, titania, montmorillonite and carbonaceous materials is required. Robustness and catalytic activity of tailor-made nanostructured catalysts outperform in many cases classical ones[90].…”