Development of New Chiral Amino Alcohol Ligand for the Asymmetric Transfer Hydrogenation of Ketones and Its Immobilization Onto Nanomaterials for an Ease of Recovery and Reuse

Abstract

This study has been carried out to extend the validation of an amino alcohol catalyst in the asymmetric transfer hydrogenation (ATH) of ketones. Previously, the catalyst was tested in asymmetric addition to several aromatic aldehydes with good to excellent results. After having optimized the reaction conditions and tested different amino residues, the best catalyst was tested in ATH of various aromatic ketones, leading to generally high yields (up to > 95%) and moderate to good enantioselectivities (ee 24%–69%). Moreover, considering the lack of examples of recoverable and reusable amino alcohol–based nanostructured catalysts for the ATH, the catalyst of choice was immobilized on proper functionalized superparamagnetic core–shell magnetite–silica nanoparticles and employed in an ATH reaction in semi-homogeneous phase. The obtained nanocatalyst exhibited a moderate catalytic efficiency in the ATH, that remains unchanged in the three catalytic cycles performed, even if noticeably worse than in the homogeneous counterpart.