Ziyuan Ding

Tianli Wang; Lian-Gang Zhuo; Zhiwei Li; Fei Chen; Ziyuan Ding; Yan-Mei He; Qing-Hua Fan; Junfeng Xiang; Zhi-Xiang Yu; Albert S. C. Chan

Asymmetric hydrogenation of quinolines catalyzed by chiral cationic η(6)-arene-N-tosylethylenediamine-Ru(II) complexes have been investigated. A wide range of quinoline derivatives, including 2-alkylquinolines, 2-arylquinolines, and 2-functionalized and 2,3-disubstituted quinoline derivatives, were efficiently hydrogenated to give 1,2,3,4-tetrahydroquinolines with up to >99% ee and full conversions. This catalytic protocol is applicable to the gram-scale synthesis of some biologically active tetrahydroquinolines, such as (-)-angustureine, and 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline, a key intermediate for the preparation of the antibacterial agent (S)-flumequine. The catalytic pathway of this reaction has been investigated in detail using a combination of stoichiometric reaction, intermediate characterization, and isotope labeling patterns. The evidence obtained from these experiments revealed that quinoline is reduced via an ionic and cascade reaction pathway, including 1,4-hydride addition, isomerization, and 1,2-hydride addition, and hydrogen addition undergoes a stepwise H(+)/H(-) transfer process outside the coordination sphere rather than a concerted mechanism. In addition, DFT calculations indicate that the enantioselectivity originates from the CH/π attraction between the η(6)-arene ligand in the Ru-complex and the fused phenyl ring of dihydroquinoline via a 10-membered ring transition state with the participation of TfO(-) anion.

Fei Chen; Ziyuan Ding; Jie Qin; Tianli Wang; Yan-Mei He; Qing-Hua Fan

A range of cyclic N-alkyl imines were efficiently hydrogenated by using a chiral cationic Ru(η(6)-cymene)(MsDPEN)(BArF) complex (MsDPEN = N-(methanesulfonyl)-1,2-diphenylethylenediamine) in high yields and up to 98% ee. A one-pot synthesis of chiral 2-phenylpyrrolidine via reductive amination was also developed.

Jie Qin; Fei Chen; Ziyuan Ding; Yan-Mei He; Lijin Xu; Qing-Hua Fan

The enantioselective hydrogenation of 2-alkyl- and 2-aryl-subsituted quinoxalines and 2,3-disubstituted quinoxalines was developed by using the cationic Ru(η(6)-cymene)(monosulfonylated diamine)(BArF) system in high yields with up to 99% ee. The counteranion was found to be critically important for the high enantioselectivity and/or diastereoselectivity.

Baode Ma; Ziyuan Ding; Ji Liu; Yan-Mei He; Qing-Hua Fan

A PHOX with arms: A series of dendrimers with Ir phosphinooxazoline (PHOX) cores were designed and synthesized and found to be highly effective and recoverable catalysts for asymmetric hydrogenation of 2,4-diaryl-1,5-benzodiazepines. An obvious positive dendritic effect on reactivity was observed, leading to chiral nitrogen-containing heterocycles with excellent enantioselectivities.

Ziyuan Ding; Fei Chen; Jie Qin; Yan-Mei He; Qing-Hua Fan

Fei Chen; Tianli Wang; Yan-Mei He; Ziyuan Ding; Zhiwei Li; Lijin Xu; Qing-Hua Fan

Ziyuan Ding; Tianli Wang; Yan-Mei He; Fei Chen; Hai-Feng Zhou; Qing-Hua Fan; Qingxiang Guo; Albert S. C. Chan

Fei Chen; Ziyuan Ding; Yan-Mei He; Jie Qin; Tianli Wang; Qing-Hua Fan

Zhusheng Yang; Ziyuan Ding; Fei Chen; Yan-Mei He; Nianfa Yang; Qing-Hua Fan

Tingting Miao; Baode Ma; Ziyuan Ding; Youran Liu; Yan-Mei He; Qing-Hua Fan