title: Assessing the suitability of 1,2,3-triazole linkers for covalent immobilization of chiral ligands: application to enantioselective phenylation of aldehydes.
abstract: Alkynyl-functionalized amino alcohols have been covalently supported on azidomethylpolystyrene resins with different levels of functionalization through Cu(I)-catalyzed 1,3-dipolar cycloadditions ("click chemistry"). The resulting 1,2,3-triazole-substituted resins, characterized by different levels of ligand loading and, depending on the nature of the alkynyl-functionalized amino alcohol, the presence of a one-carbon, four-carbon, or eight-carbon linear spacer, have been tested as catalysts in the enantioselective phenyl transfer from zinc to aldehydes. High catalytic activities and enantioselectivities (up to 82% ee) have been recorded. The influence of structural characteristics of the resin on enantioselectivity are discussed, and the limitations in enantiocontrol inherent to the use of a 1,2,3-triazole linker have been rationalized with the help of DFT calculations on model systems.
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona, Spain.
authors.forename: Amaia
authors.initials: A
authors.lastname: Bastero
authors.forename: Daniel
authors.initials: D
authors.lastname: Font
authors.forename: Miquel A
authors.initials: MA
authors.lastname: Pericàs