Sabir Ahammed

Copper Nanoparticle-Catalyzed CarbonCarbon and CarbonHeteroatom 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.

Solvent-free one-pot synthesis of 1,2,3-triazole derivatives by the ‘Click’ reaction of alkyl halides or aryl boronic acids, sodium azide and terminal alkynes over a Cu/Al2O3 surface under ball-milling

A one-pot procedure for the synthesis of 1,2,3-triazole derivatives by a three-component coupling of alkyl (benzyl) halides or aryl boronic acids, sodium azide and terminal alkynes over copper(II) sulfate supported on alumina (Cu/Al2O3) under ball-milling in the absence of any solvent and additive has been developed. The product was isolated by simple washing of the crude reaction residue with ethanol followed by evaporation of the solvent. No chromatographic purification is required. The catalyst is recycled for subsequent reactions. The azides are produced in situ and thus this procedure avoids the handling of hazardous azides. This protocol offers broad scope for access to a variety of diversely substituted 1,2,3-triazoles. The use of no hazardous organic solvent, the use of ball-milling, and cost efficiency, recyclability of the catalyst up to eight runs without appreciable loss of activity and high yields of products make this procedure greener.

tert-Butyl Nitrite Mediated Regiospecific Nitration of (E)-Azoarenes through Palladium-Catalyzed Directed CH Activation

An efficient protocol for the Pd-catalyzed regiospecific ortho-nitration of (E)-azoarenes has been achieved for the first time using tBuONO as a nitrating agent under atmospheric oxygen. A series of both symmetrical and unsymmetrical azoarenes were nitrated efficiently by this procedure providing excellent chemo- and regioselectivity and compatibility with a broad array of functional groups.

Microwave-assisted reaction of aryl diazonium fluoroborate and diaryl dichalcogenides in dimethyl carbonate: a general procedure for the synthesis of unsymmetrical diaryl chalcogenides

A convenient, general and efficient procedure for the synthesis of unsymmetrical diaryl chalcogenides has been developed by the reaction of aryl diazonium fluoroborates and diaryl dichalcogenides in the presence of zinc dust in dimethyl carbonate under microwave irradiation. The reactions of a wide range of substituted aryl diazonium fluoroborates and diaryl dichalcogenides have been addressed. The zinc dust is required for the cleavage of diaryl dichalcogenides. The products are obtained in high purity after fast column chromatography of the crude residue after evaporation of dimethyl carbonate.

Ruthenium catalysed one-pot synthesis of S-allyl and cinnamyl dithiocarbamates using allyl and cinnamyl acetates in water

A convenient and efficient procedure for the synthesis of S-allyl/cinnamyl dithiocarbamates has been developed by a one-pot reaction of allyl/cinnamyl acetate, carbon disulfide and amine in presence of Ru(acac)3 in water. A variety of functionalized dithiocarbamates have been obtained by this procedure in high yields. The reaction proceeds via a catalytic Ru(II) species, generated in situ during the reaction.