The influence of the alcohol, as the hydrogen donor, on the efficiency and selectivity of the asymmetrictransferhydrogenation (ATH) of imines is reported for the first time. This discovery not only leads to a highly enantioselective access to N‐aryl and N‐alkyl amines, but also provides new insight into the mechanism of the ATH of imines. Both experimental and computational studies provide support
Catalytic Asymmetric Hydrogenation of Imines with a Chiral Titanocene Catalyst: Scope and Limitations
作者:Christopher A. Willoughby、Stephen L. Buchwald
DOI:10.1021/ja00099a012
日期:1994.10
The asymmetric hydrogenation of imines with a chiral titanocene catalyst derived from Brintzinger's ansatitanocene complex 1 proceeds to afford amines with good to excellent enantioselectivity. The catalyst is particularly effective for the reduction of cyclic imines. For these substrates enantiomeric excesses from 95 to 99% were achieved. For acyclic imines lower enantiomeric excesses were observed. The reason for this is likely due to the fact that the acyclic imines are mixtures of anti and syn isomers which interconvert during the reaction. The catalyst was found to be tolerant of many functional groups found in organic synthesis. Thus the reaction represents an effective method for the synthesis of chiral cyclic amines.
Base-Catalyzed [3 + 2] Cycloaddition of <i>N-</i>Benzyl Ketimines to Arylacetylenes Followed by Oxidation: A One-Pot Access to Polyarylated 2<i>H</i>-Pyrroles via Intermediate Pyrrolines
作者:Ivan A. Bidusenko、Elena Yu. Schmidt、Igor A. Ushakov、Alexander V. Vashchenko、Boris A. Trofimov