Asymmetric hydrogenation of N-alkyl and N-aryl ketimines using chiral cationic Ru(diamine) complexes as catalysts: the counteranion and solvent effects, and substrate scope
作者:Fei Chen、Ziyuan Ding、Yanmei He、Jie Qin、Tianli Wang、Qing-Hua Fan
DOI:10.1016/j.tet.2012.03.019
日期:2012.7
Asymmetrichydrogenation of N-alkyl and N-aryl ketimines catalyzed by chiralcationic η6-arene-(N-monosulfonylated diamine) Ru(II) complexes has been investigated. Strong counteranion and solvent effects on the enantioselectivity were observed. The ruthenium catalyst bearing non-coordinating BArF− anion was found to be particularly effective for the hydrogenation of acyclic and exocyclic N-alkyl ketimines
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.
Hydroboration Catalyzed by 1,2,4,3-Triazaphospholenes
作者:Chieh-Hung Tien、Matt R. Adams、Michael J. Ferguson、Erin R. Johnson、Alexander W. H. Speed
DOI:10.1021/acs.orglett.7b02695
日期:2017.10.20
shown to catalyze the 1,2 hydroboration of 19 imines, and three α,β unsaturated aldehydes with pinacolborane, including examples that did not undergo hydroboration by previously reported diazaphospholene systems. DFT calculations support a mechanism where a triazaphospholene cation interacts with the substrate, a mechanism distinct from diazaphospholene catalyzed hydroborations.