A new class of oxazoline ligands, named SupraBox, was studied. These ligands possess an additional urea functionality to generate supramolecular bidentate ligands in transition-metal complexes, by the establishment of hydrogen bonds between the urea N-hydrogens of one ligand and the carbonyl oxygen of a second one. A library of 16 SupraBox ligands was prepared using 5 differently substituted oxazoline nuclei, 4 linkers and 3 different urea substituents. The formation of copper(II) and palladium(II) complexes was investigated by MS, UV/Vis and 1H-NMR spectroscopy. The SupraBox library was screened in the copper-catalyzed asymmetric benzoylation of vic-diols. Good selectivities were obtained in the kinetic resolution of racemic hydrobenzoin [up to 86 % ee and selectivity (s) = 28] and in the desymmetrization of meso-hydrobenzoin (up to 88 % ee).
|Titolo:||SupraBox: chiral supramolecular oxazoline ligands|
|Parole Chiave:||Acylation; Asymmetric catalysis; N ligands; Self-assembly; Supramolecular chemistry|
|Settore Scientifico Disciplinare:||Settore CHIM/06 - Chimica Organica|
|Data di pubblicazione:||lug-2012|
|Digital Object Identifier (DOI):||10.1002/ejoc.201200516|
|Appare nelle tipologie:||01 - Articolo su periodico|