Copper nanoparticles supported on silica coated maghemite as versatile, magnetically recoverable and reusable catalyst for alkyne coupling and cycloaddition reactions

A versatile and magnetically recoverable catalyst consisting of copper nanoparticles on silica coated maghemite nanoparticles (MagSilica (R)) is presented. The catalyst has been prepared under mild conditions by fast reduction of anhydrous CuCl2 with lithium sand and a catalytic amount of DTBB (4,4'-di-tert-butylbiphenyl) as electron carrier, in the presence of the magnetic support. The catalyst has been fully characterized and its performance in different coupling and cycloaddition reactions of terminal alkynes has been studied. This new copper-based catalyst has shown to be very efficient and easily reusable in the Glaser alkyne dimerization reaction in THF, the multicomponent Huisgen 1,3-dipolar cycloaddition reaction in water and the three-component synthesis of propargylamines under solvent free conditions. (c) 2013 Elsevier B.V. All rights reserved.