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
N-Benzylamines are prepared by a process in which
(i) in a first step, a benzaldehyde is reacted with a primary amine to give the imine and
(ii) in a second step, the imine is hydrogenated with hydrogen in the presence of a catalyst containing one or more metals of groups 8 to 10 of the Periodic Table of the Elements to give the N-benzylamine,
wherein the iminization (i) is carried out in a water-miscible solvent and the resulting water of reaction is not removed, and the hydrogenation (ii) is carried out in the imine solution obtained in the iminization (i) and containing water of reaction.
N-苄胺是通过以下过程制备的:
(i) 在第一步中,苯甲醛与一级胺反应生成亚胺,
(ii) 在第二步中,在元素周期表8至10族中的一个或多个金属催化剂存在下,将亚胺与氢气加氢反应生成N-苄胺,
其中亚胺化反应(i)在水溶性溶剂中进行,生成的反应水不被去除,而加氢反应(ii)在亚胺化反应(i)中获得的亚胺溶液中进行,其中含有反应水。
A Chiral “Roofed” cis-Diamine-Ru(II) Complex: An Efficient Catalyst for Asymmetric Transfer Hydrogenation of Ketimines
Highly enantioselective transferhydrogenation of ketimines to the corresponding chiral amines was achieved with the chiral Ru(II) complex, prepared from the conformationally rigid and sterically bulky "roofed" cis-1,2-diamine.
N-Benzylamines are prepared by a process in which
(i) in a first step, a benzaldehyde is reacted with a primary amine to give the imine and
(ii) in a second step, the imine is hydrogenated with hydrogen in the presence of a catalyst containing one or more metals of groups 8 to 10 of the Periodic Table of the Elements to give the N-benzylamine,
wherein the iminization (i) is carried out in a water-miscible solvent and the resulting water of reaction is not removed, and the hydrogenation (ii) is carried out in the imine solution obtained in the iminization (i) and containing water of reaction.
most efficient methods for amine synthesis. Herein we report a practical homogeneous DRA procedure utilizing iridium catalysis. Applying simple, readily available and inexpensive PPh3 and alike ligands along with iridium at a low loading, aldehydes and ketones reductively coupled with primary and secondary amines to efficiently form structurally and functionally diverse amine products, including a set