Enantioselective synthesis of 2-oxazolidinones by ruthenium(ii)–NHC-catalysed asymmetric hydrogenation of 2-oxazolones†
An efficient synthesis of optically active 4-substituted 2-oxazolidinones by the ruthenium(II)–NHC-catalysed asymmetric hydrogenation of 2-oxazolones was developed. Excellent enantioselectivities (up to 96% ee) and yields (up to 99%) were obtained for a variety of substrates, bearing a range of functional groups and useful motifs. The hydrogenation reaction was successfully scaled up to gram scale using low catalyst loading. Moreover, the utility of this methodology was demonstrated by the transformation of the enantioenriched product into the corresponding chiral β-amino alcohol, a bisoxazoline ligand, and the formal synthesis of (−)-aurantioclavine.