Catalytic sugar-assisted transfer hydrogenation with Ru(II), Rh(III) and Ir(III) halfsandwich complexes

•Arene complexes with sugar ligands were applied in asymmetric transfer hydrogenation.•The complexes under study induce an enantiomeric excess up to 66%.•The D-gluco- and D-mannopyranoside ligands behave as pseudo-enantiomers.•The enantiomeric excess is supported by the substitution pattern of the arene ligands.•With DFT calculations the favored transition states could be identified.

The application of halfsandwich ruthenium(II), rhodium(III) and iridium(III) complexes of four different methyl 2,3-diamino-4,6-O-benzylidene-2,3-dideoxy-α-D-hexopyranosides and a methyl 2-amino-3-tosylamido-α-D-glucopyranoside as catalyst precursors in asymmetric transfer hydrogenation of acetophenone is reported. The configuration of the hexopyranosides and the type of arene ligands determine the formation of R- or S-1-phenylethanol up to 66% ee. A large influence of the substitution pattern of the arene ligands on the extent of the enantiomeric excess is demonstrated. The results are interpreted by means of DFT calculations.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (122 K)Download as PowerPoint slide