NEW C-2-SYMMETRICAL FERROCENYL DIAMINES AS LIGANDS FOR RUTHENIUM-CATALYZED TRANSFER HYDROGENATION

The new C-2-symmetrical ferrocenyl diamines 5-7 and 13 proved to be go od ligands for the ruthenium catalyzed enantioselective transfer hydro genation of unsymmetrical ketones. The stereocontrolled and highly fle xible synthetic route to the new diamines made it possible to vary the ligand structure in an efficient manner. A short trial and error proc ess led to a very active catalytic system with diamine 6a as the ligan d, which is capable of reducing ketones even at -30 degrees C using 2- propanol as a hydrogen source. Enantioselectivities up to 90% were rea ched in the reduction of 1'-acetonaphthone. (C) 1998 Elsevier Science Ltd. All rights reserved.