Copper Nanoparticle‐Catalyzed CarbonCarbon and CarbonHeteroatom Bond Formation with a Greener Perspective

Abstract

The carbon-carbon and carbon-heteroatom bond formations constitute the backbone of organic synthesis and have been widely used in the synthesis of natural products and useful compounds. Because of growing environmental concern, more attention has been focussed on the development of greener methods. Copper is environment-friendly and comparatively inexpensive. Although the use of copper salts in catalysis has been known since the last century, this area of research has been less explored compared to other metals, such as palladium, magnesium, and zinc. This review highlights the general features of nanoparticles as catalysts with particular reference to copper and the recent developments in the copper(0) nanoparticle-catalyzed C(aryl)-C(aryl/alkynyl), C(aryl)-N, C(aryl)-O, C(aryl)-S, and C(aryl)-Se bond formations and related reactions. The mechanisms of the reactions have been outlined and discussed with respect to the active catalytic species and possible intermediates. The scope, limitations, and green aspects of the reactions have also been highlighted. The convenient methods of preparation of copper nanoparticles and their characterization are described.

Ligand-free copper(i) oxide nanoparticle-catalysed amination of aryl halides in ionic liquids

“…18,19 However, up to now nanoscale copper(I) catalysed cross coupling reactions, especially C-N bond formation, have rarely been reported in scientific literature 13,[20][21][22] or show drawbacks in versatility and catalyst loadings. 20,[22][23][24][25] Furthermore, it would be more convenient to conduct catalysis at temperatures right below the boiling point of water without the necessity for ligands, additives and inert reaction conditions. 26 Nonetheless, we want to establish a Cu 2 Onanocatalyst which combines the advantages of classical homogeneous and heterogeneous catalyses.…”

Novel radical tandem 1,6-enynes thioacylation/cyclization: Au–Pd nanoparticles catalysis versus thermal activation as a function of the substrate specificity

“…Finally, we modified the electron-withdrawing groups E on the tether with substrates 6a and 7a, derived from ethyl acetoacetate and pentane-2,4-dione, respectively. In the presence of AuePd NPs, the cyclized products 6b and 7b were formed with good to excellent selectivities and moderate to excellent conversions (entries 8,9).…”

Sol–gel entrapped Cu in a silica matrix: An efficient heterogeneous nanocatalyst for Huisgen and Ullmann intramolecular coupling reactions

“…Two good examples of reactions in which copper(I) plays a central role are the well-established Huisgen Copper Alkyne-Azide Cycloaddition (CuAAC) [16][17][18][19][20][21] and the Ullmann reaction [22]. A current trend in these transformations is the heterogenization of the catalyst [23][24][25][26][27][28][29][30][31][32][33][34]. While current methodologies represent major progress in this field, challenges associated with the synthesis, reactivity and leaching profiles of these catalytic systems remain partially unsolved.…”