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
Intramolecular Diels-Alder reactions of furanderivatives each containing a trifluoromethyl group in the dienophilic part or the tethering chain of the dienophile to the furan ring showed a notable electronic effect of the trifluoromethyl group on the stereoselectivity. The electronic effect of the trifluoromethyl group was confirmed by results of a comparison with other substituents (phenyl, methyl
Chiral catalyst and method for asymmetric reduction of an imine
申请人:DALHOUSIE UNIVERSITY
公开号:US11161863B2
公开(公告)日:2021-11-02
The present disclosure discusses (i) a compound having a chemical formula according to Formula (I), or its enantiomer; and (ii) a compound that is reactive with a hydride to produce a compound having a chemical formula according to Formula (I), or its enantiomer. Formula (I) is: Formula (I) where R1 and R2 are H, optionally substituted C1-C3 alkyl, or linked together to form an optionally substituted C3 or C4 alkyl group; R3 and R3′ are H; R4 and R4′ are the same, and are optionally substituted C1-C6 alkyl; and R5 and R5′ are the same, and are optionally substituted aryl or heteroaryl. In some examples, R4 and R5 are linked, and R4′ and R5′ are linked, where both linking groups are the same. The present disclosure also discusses methods of asymmetric reduction of an imine, and methods of forming the catalysts and pre-catalysts.
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.