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®) 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.

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► Copper nanoparticles on nanosized magnetic support as catalyst for alkyne synthetic transformations.
► Commercially available silica coated maghemite (MagSilica) is used as magnetic support.
► The nanocatalyst is easily recovered and reused by means of an external magnet.
► High versatility of the catalyst for high atom economy alkyne coupling and cycloaddition reactions.