Cobalt-Catalyzed Asymmetric Hydrogenation of 1,1-Diarylethenes
作者:Jianhui Chen、Chenhui Chen、Chonglei Ji、Zhan Lu
DOI:10.1021/acs.orglett.6b00453
日期:2016.4.1
Highlyenantioselective cobalt-catalyzed hydrogenation of 1,1-diarylethenes was developed by using bench-stable chiral oxazoline iminopyridine–cobalt complexes as precatalysts. A unique o-chloride effect was observed to achieve high enantioselectivity. Easy removal as well as further transformations of the chloro group make this protocol a potentially useful alternative to synthesize various chiral
Nickel-Catalyzed Asymmetric Hydroarylation of Vinylarenes: Direct Enantioselective Synthesis of Chiral 1,1-Diarylethanes
作者:Hai N. Tran、Russell W. Burgett、Levi M. Stanley
DOI:10.1021/acs.joc.0c02556
日期:2021.3.5
The enantioselective hydroarylation of vinylarenes catalyzed by a chiral, non-racemic nickel catalyst is presented as a facile method to generate chiral 1,1-diarylethanes. These reactions proceed via formation of a chiral, non-racemic nickel benzyl intermediate. Transmetalation with arylboron nucleophiles and subsequent reductive elimination enable the formation of a variety of chiral 1,1-diarylethanes
Chiral iridium complexes ligated by anionic oxazoline-bearing NCP-type pincer ligands were developed and applied to the asymmetric transfer hydrogenation (ATH) of diarylethenes using environmentally benign ethanol as the hydrogen donor. High enantioselectivities could be achieved for substrates bearing ortho-Me, ortho-Cl, or ortho-Br substituents on one of the aryl groups. The ATH of ortho-Br-substituted
开发了由带有阴离子恶唑啉的 NCP 型钳形配体连接的手性铱配合物,并将其应用于使用环境友好型乙醇作为氢供体的二芳基乙烯的不对称转移氢化 (ATH)。对于在芳基之一上带有邻-Me、邻-Cl或邻-Br取代基的底物可以实现高对映选择性。由于 C (芳基) -Br 键易于经历各种新的键形成事件,邻位-Br 取代的二芳基乙烯的 ATH特别有吸引力。
Highly Enantioselective Hydrogenation of Styrenes Directed by 2′-Hydroxyl Groups
作者:Xiang Wang、Anil Guram、Seb Caille、Jack Hu、J P. Preston、Michael Ronk、Shawn Walker
DOI:10.1021/ol200422p
日期:2011.4.1
A new synthetic strategy that turns styrene-type olefins into excellent substrates for Rh-catalyzed asymmetric hydrogenation by Installing a 2'-hydroxyl substituent is described. This methodology accommodates trisubstituted olefinic substrates in various E/Z mixtures, leading to valuable benzylic chiral compounds including (R)-tolterodine. It is also demonstrated that the 2'-hydroxyl groups could be readily removed in high yield without loss of ee from the products. Thus, this technology represents an attractive alternative to the Ir(P-N) catalyst system for the asymmetric hydrogenation of unfunctionalized olefins.
Organocatalytic Asymmetric Nucleophilic Addition to <i>o</i>-Quinone Methides by Alcohols
作者:Zengwei Lai、Zhaobin Wang、Jianwei Sun
DOI:10.1021/acs.orglett.5b03072
日期:2015.12.18
The first catalytic asymmetric intermolecular alcohol conjugate addition to o-quinone methides (o-QMs) is disclosed. Due to reversible C-O bond formation and low nucleophilicity of alcohols, catalytic asymmetric oxa-Michael additions with simple alcohol nucleophiles to establish acyclic oxygenated carbon stereocenters remain scarce. The present reaction represents a rare example of this type. With a suitable chiral acid catalyst, the in situ formation of o-QMs and subsequent conjugate addition proceeded with high efficiency and enantioselectivity. The chiral ether products are versatile precursors to other chiral molecules.