Copper nanoparticle-catalyzed carbon-carbon and carbon-heteroatom bond formation with a greener perspective

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.