Département de chimie moléculaire

In this article the first example of a heterogeneous photolatent catalyst for the copper-catalyzed azide-alkyne cycloaddn. (CuAAC) that is supported on chitosan is reported. The heterogeneous copper(II) precatalyst was easily prepd. by reaction of [CuII2(3-benzoylbenzoate)4(H2O)2] complex with chitosan powder. UV-vis and EPR spectroscopy studies demonstrated that the Cu(II) ions are effectively photoreduced by low-intensity UVAs. In particular, it was shown that the benzophenone photosensitizer, could be employed in catalytic amt., i.e. 10 mol{%} with respect to the Cu2+ ions, to effectively promote the Cu(II) to Cu(I) photoredn. process. A range of triazoles, in particular those bearing sugar moieties, could be effectively synthesized under light illumination and sodium ascorbate-free conditions.ICP anal. did not show copper contamination of the final product, thereby evidencing tight incorporation of copper on the chitosan powder. Owing to its heterogeneous nature, the catalyst could be recovered and reused several times with no appreciable decrease in the catalytic activity. As a practical application of the procedure, the anticonvulsant drug rufinamide was isolated in 82{%} yield on a 10 mmol scale synthesis. [on SciFinder(R)]