Ruthenium complexes, prepared by mixing the potassium salt of a-amino acids and [RuCl 2 (arene)] 2 , acted as catalysts for the asymmetric transfer hydrogenation of ketones from 2-propanol in the presence of KOH. For example, the transfer hydrogenation of acetophenone from 2-propanol was catalyzed effectively by the ruthenium complex prepared from potassium L-prolinate and [RuCl 2 (p-cymene)] 2 to give (R)-1-phenylethanol in 72% yield with 81% ee. The yields and enantioselectivities of the product were influenced strongly by the structure of the a-amino acidate ligand, arene ligand, and substrate, by the amount of additional base, and by the concentration of the substrates. The best enantiomeric excesses of the products was 92%, when 1-tetralone was subjected to this reaction using a prolinated ruthenium complex bearing p-cymene. Furthermore, the potassium salts of dipeptides were tested as a ligand for this transfer hydrogenation.

Ruthenium complexes, prepared by mixing potassium salt of α-amino acids and [RuCl2(arene)]2, acted as catalysts for asymmetric transfer hydrogenation of ketones from 2-propanol in the presence of KOH, and enantiomeric excesses of the products reached 92%.

stereochemistry stereochemistry (general, optical resolution) O 0030 44 -041 α-Amino Acidate-Ru(II) Catalysts for Asymmetric Transfer Hydrogenation: First Utilization of α-Amino Acids as an Efficient Ligand. -Ru-complexes (I) derived from potassium salts of α-amino acids and Ru 2 Cl 4 (arene) 2 prove to be efficient catalysts for the asymmetric transfer hydrogenation of ketones from alcohols. Enantiomeric excesses of the products reach 92%. -(OHTA, T.; NAKAHARA, S.; SHIGEMURA, Y.; HATTORI, K.; FURUKAWA, I.; Chem. Lett. (1998) 6, 491-492; Dep. Mol. Sci. Technol., Fac. Eng., Doshisha Univ., Tanabe, Kyoto 610-03, Japan; EN)

diastereoselective syntheses, enantioselective syntheses diastereoselective syntheses, enantioselective syntheses (incl. cis/trans-isomerism) O 0031 -027α-Amino Acid: An Effective Ligand for Asymmetric Catalysis of Transfer Hydrogenation of Ketones.-19 Amino acids and 16 dipeptides are tested as ligands for asymmetric transfer hydrogenation of prochiral ketones. The corresponding ruthenium catalysts are prepared from [RuCl 2 (p-cymene)] 2 and the potassium salt of the amino acid or dipeptide, respectively. Best results are obtained using proline-derived catalyst RCPC (cf. scheme). This reaction is lauded to provide the first efficient asymmetric catalytic method directly using an α-amino acid as a ligand.-(OHTA,

Bei der katalytischen Hydrogenierung an Pd‐Kohle der Titelverbindung (I) entsteht neben den Aminen (IIIa)‐(IIIc) das neuartige tricyclische Lactam (II).