Triazole-based ligands for click chemistry and asymmetric catalysis

Abstract

In this thesis, different approaches for the application of click chemistry to the preparation of catalysts and ligands are developed. Several strategies towards the use of 1,2,3-triazoles from copper-catalyzed azide-alkyne cycloaddition(CuAAC) reaction as click ligands are explored. Mainly, 1,2,3-triazole is used as donor groups for transition metal complexes in metal-catalyzed reactions, following on the simplicity of the synthetic route. In particular, CuAAC reaction is used to synthesize triazole-based ligands and later, for the first part of the project, tris(triazolyl)methanol•copper(I) chloride complexes are used in order to catalyze CuAAC very efficiently, on water, neat, under microwave irradiation and in organic solvents. Under all optimized conditions excellent yields are obtained. Then, the covalent immobilizations of these ligands are succeeded onto Merrifiled resin with 5 reuses and a broad functional group tolerance. In the second part of the thesis, triazole-based ligands are further developed for metal-catalyzed asymmetric transformations. Particularly, for molybdenum-catalyzed asymmetric allylicalkylations excellent enantio- nadregio-selectivities are achieved both under conventional and microwave assisted conditions with a very broad scope. Finally, ligands for enantioselective copper-catalzyed conjugate addition of diethylzinc are established under optimized conditions very good conversion are obtained albeit moderate ee. In general, the metal/triazole-based ligand complexes are used as catalysts in CuAAC reaction and catalytic asymmetric transformations.