alpha-Amino acid: an effective ligand for asymmetric catalysis of transferhydrogenation of ketones

Citation
T. Ohta et al., alpha-Amino acid: an effective ligand for asymmetric catalysis of transferhydrogenation of ketones, APPL ORGAN, 15(8), 2001, pp. 699-709
Citations number
44
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry
Journal title
APPLIED ORGANOMETALLIC CHEMISTRY
ISSN journal
0268-2605 → ACNP
Volume
15
Issue
8
Year of publication
2001
Pages
699 - 709
Database
ISI
SICI code
0268-2605(200108)15:8<699:AAAELF>2.0.ZU;2-Q
Abstract
Ruthenium complexes, prepared by mixing the potassium salt of alpha -amino acids and [RuCl2(arene)](2), acted as catalysts for the asymmetric transfer hydrogenation of ketones from 2-propanol in the presence of KOH. For examp le, the transfer hydrogenation of acetophenone from 2-propanol was catalyze d effectively by the ruthenium complex prepared from potassium L-prolinate and [RuCl2(p-cymene)](2) to give (R)-1-phenylethanol in 72% yield with 81% ee. The yields and enantioselectivities of the product were influenced stro ngly by the structure of the a-amino acidate ligand, arene ligand, and subs trate, by the amount of additional base, and by the concentration of the su bstrates. The best enantiomeric excesses of the products was 92%, when 1-te tralone was subjected to this reaction using a prolinated ruthenium complex bearing p-cymene. Furthermore, the potassium salts of dipeptides were test ed as a ligand for this transfer hydrogenation. Copyright (C) 2001 John Wil ey & Sons, Ltd.