A series of novel tridentate ligands with nitrogen and oxygen donor sites was synthesized starting from enantiomerically
pure (
S)- and (
R)-1-(pyridin-2-yl)ethylamine, the preparation and resolution of which was developed. The new optically active ligands were
tested as
in situ catalysts together with Ru(PPh
3)
3Cl
2 in the enantioselective transfer hydrogenation of acetophenone with isopropanol. The secondary amine ligand (
S)-2,4-di-
tert-butyl-6-(1-(pyridin-2-yl)ethylamino)methylphenol gave the best results with almost quantitative conversion and 47%
ee.
Keywords. Catalysis; Chirality; Transfer hydrogenation; Tridentate ligands.
Received August 17, 2001. Accepted August 27, 2001