Asymmetric catalytic reduction of carbonyl compounds using C2 symmetric diamines as chiral ligands

✍ Scribed by Patrick Gamez; Fabienne Fache; Marc Lemaire

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 696 KB
• Volume: 6
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/0957-4166(95)00067-y

✦ Synopsis

The catalytic asymmelxic reduction of prochiral ketones by hydride transfer using various C2 symmelric chiral diamines as ligands and rhodium complexes is studied. Kinetic studies show an increase of the enantiomeric excess with the conversion.

Nitrogen containing ligands are more and more used in asymmetric catalysis I for reactions as different as carbonyl reduction 2.3 or allylic alkylation 4 ..... They present many advantages upon their phosphorus analogs (accessibility, easy recovering,...) and in the future they could probably replace phosphines in some cases.

Optically active disymmetric alkylphenanthrolines have been shown by Gladiali 5 et al. to be efficient ligands in enantioselective reduction of acetophenone by hydride transfer in the presence of rhodium catalysts :

up to 65% e.e. has been obtained and a mechanism has been proposed based on UV analyses and investigations on the influence of different parameters. According to the authors, a catalytic cycle for the hydrogenation of acetophenone by hydride transfer starting from compound I, can be drawn as reported in Figure 1.