Selective Diethylzinc Reduction of Imines in the Presence of Ketones Catalyzed by Ni(acac)2
摘要:
A selective reduction method of an electronically deficient imine in the presence of ketone was developed by employing Et2Zn and 5 mol % of Ni(acac)(2). The method was applied in the reduction of S-S-tert-butanesultinyl ketimines 1 to afford amines 2 in 23-92% yields and 73:27 to 98:2 diastereoselectivities. A plausible mechanism was proposed on the basis of an NMR study.
Asymmetric synthesis of N-protected amino acids by the addition of organolithium carboxyl synthons to ROPHy/SOPHy-derived aldoximes and ketoximesChiral oxime ethers in asymmetric synthesis. Part 6.1
作者:Tracey S. Cooper、Pierre Laurent、Christopher J. Moody、Andrew K. Takle
DOI:10.1039/b310624a
日期:——
hydroxylamines, followed by N-protection, and oxidativecleavage of the carboxyl precursor gave a range of N-protected amino acids and esters. The method was exemplified by the synthesis of a range of derivatives of non-proteinogenic amino acids such as 4-bromophenylalanine, tert-leucine, norvaline, cyclohexyl- and aryl-glycines, 2-amino-8-oxodecanoic acid (Aoda) and alpha-methylvaline.
Diastereoselective addition of organolithiums to new chiral hydrazones. Enantioselective synthesis of (R)-coniine
作者:Yong Hae Kim、Jun Young Choi
DOI:10.1016/0040-4039(96)01151-3
日期:1996.7
The reactions of organolithiums with the new chiral hydrazones derived from (S)-indoline-2-carboxylic acid afforded chiral hydrazines with high diastereoselectivities (up to 99% de) and the present method was utilized for the preparation of high optically pure (R)-coniine (94% ee).
Comparative Study of Bifunctional Mononuclear and Dinuclear Amidoiridium Complexes with Chiral C−N Chelating Ligands for the Asymmetric Transfer Hydrogenation of Ketones
作者:Yasuhiro Sato、Yoshihito Kayaki、Takao Ikariya
DOI:10.1002/asia.201600955
日期:2016.10.20
amido‐bridged dinuclear complexes (3 a and 3 a’), more sterically hindered complexes were solely transformed into the coordinatively unsaturated mononuclear amido complexes (3 b and 3 c), which can serve as real catalystspecies in the asymmetric transfer hydrogenation. The structural difference in the C−N chelate framework markedly affected the catalytic performance. Among them, amido complex 3 c showed a pronounced
通过光学活性的伯苄胺如O-甲硅烷基化(S)-2-氨基-2-苯基乙醇(1a和1a'),(R)-5-氨基-6,7,8,9-四氢-5 H-苯并环庚烯(1 b)和(R)-1-苯基-2-2,2-二甲基丙胺(1 c)。尽管用源自1a和1a'的胺络合物处理KO t Bu可以得到酰胺桥联的双核络合物(3a和3a'),空间位阻较大的配合物仅转化为配位不饱和的单核酰胺配合物(3b和3c),可在不对称转移氢化反应中用作真正的催化剂。CN螯合物骨架中的结构差异显着影响了催化性能。其中,即使在−30°C的低温下,酰胺基络合物 3 c仍具有明显的催化苯乙酮在2-丙醇中转移氢化的能力。在2丙醇中3 c的反应中还发现了氢化铱络合物(4 c),这为将氢转移到前手性酮中的对映异构步骤提供了机械原理的见解。
Asymmetric Synthesis of α-Branched Primary Amines on Solid Support via Novel Hydrazine Resins
作者:Dieter Enders、Jan H. Kirchhoff、Johannes Köbberling、Thomas H. Peiffer
DOI:10.1021/ol015721x
日期:2001.4.1
[reaction: see text]. Two novel chiral hydrazine resins for asymmetric solid-phase synthesis have been developed. The enantiopure beta-methoxyamino auxiliaries, derived from trans-4-hydroxy-(S)-proline and (R)-leucine, were attached to Merrifield resin and transformed into their corresponding hydrazines. Immobilization of various aldehydes, followed by 1,2-addition of organolithium reagents to the
New Chiral N-Heterocyclic Carbene Ligands in Palladium-Catalyzed α-Arylations of Amides: Conformational Locking through Allylic Strain as a Device for Stereocontrol
作者:Yi-Xia Jia、Dmitry Katayev、Gérald Bernardinelli、Thomas M. Seidel、E. Peter Kündig
DOI:10.1002/chem.201000031
日期:——
Enders/Herrmann‐type chiral N‐heterocyclic carbene (NHC) ligands have been developed and applied in asymmetric palladium‐catalyzed intramolecular α‐arylations of amides. The best ligands feature the bulky tert‐butyl group and ortho‐substituted aryl groups at the stereogenic centers. Aryl bromides readily react at room temperature and aryl chlorides at 50 °C. The highly enantiomerically enriched (up