Combining Magnetic Resonance Spectroscopies, Mass Spectrometry, and Molecular Dynamics: Investigation of Chiral Recognition by 2,6-di-<i>O</i>-Methyl-β-cyclodextrin
the structurally related amine precursors of nitroxides. NOE data suggested that inclusion of the stereogenic center in the DM-beta-CD cavity occurs only when the R substituent linked to the chiral carbon contains an aromatic ring. For these types of complexes, molecular dynamics simulation indicated that the depth of penetration of the stereogenic center into the cyclodextrincavity is determined by
EPR 光谱已被用于研究 heptakis-(2,6-O-二甲基)-β-环糊精 (DM-β-CD) 和不同对映异构体对的通用结构 PhCH2NO.CH(R) 手性氮氧化物之间的复合物的形成R'。自由基和所含自由基浓度的准确平衡测量提供了这些氮氧化物的结合常数值。DM-β-CD 复合物的立体化学与复合热力学之间的关系通过将 EPR 数据与 1H-1H NOE 测量相关联,对 DM-β-CD 和结构相关的硝基氧胺前体之间的复合物进行了测量。NOE 数据表明,仅当与手性碳相连的 R 取代基包含芳香环时,才会在 DM-β-CD 腔中包含立体中心。对于这些类型的复合物,分子动力学模拟表明立体中心渗透到环糊精腔中的深度由不对称碳上的第二个取代基 (R') 的性质决定,并且是观察到的手性选择性的原因。质谱分析表明,对于目前研究的胺,通过 ESI-MS 检测到 CD 与质子化胺的静电外部加合物。
Optical Resolution of<i>dl</i>-<i>threo</i>-2-(2,4-Difluorophenyl)-2-[1-(methylthio)ethyl]oxirane: Its Application to the Synthesis of SM-9164, a Biologically Active Enantiomer of Antifungal Agent SM-8668
作者:Hiroshi Miyauchi、Naohito Ohashi
DOI:10.1246/bcsj.68.3591
日期:1995.12
carboxylic acid, followed by separation of the resultant diastereomers, hydrolysis of the ester, and dehydration of the 1,2-diol to the oxirane. This new optical resolution method was applied to the synthesis of SM-9164, a biologically active enantiomer of antifungal agent SM-8668. Thus, the opticallyactive isomer of SM-8668 was prepared efficiently in eight steps from m-difluorobenzene.
Direct Synthesis of Amides from Coupling of Alcohols and Amines Catalyzed by Ruthenium(II) Thiocarboxamide Complexes under Aerobic Conditions
作者:Elangovan Sindhuja、Rengan Ramesh、Sundarraman Balaji、Yu Liu
DOI:10.1021/om500556b
日期:2014.8.25
the ruthenium(II) thiocarboxamide complexes were generated as highly efficient catalysts for synthesis of secondary or tertiary amides by coupling of amines and alcohols with low catalyst loading, and the maximum yield was obtained up to 97%. The coupling reaction can be readily carried out under mild aerobic conditions, and release of water is the only byproduct. Further, the effect of substituents
Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer catalysts to promote the base hydrolysis of N-protected aminoacid hexafluoroisopropyl esters in a CHCl3/NaOH (aq) via dynamic kinetic resolution, providing the corresponding products in moderate to good yields (up to 99%)
Chemo-enzymatic asymmetric synthesis of amino acids. Enantioselective hydrolyses of 2-phenyl-oxazolin-5-ones.
作者:Rui-Lin Gu、Ik-Soo Lee、Charles J. Sih
DOI:10.1016/0040-4039(92)88111-h
日期:1992.4
Porcine pancreatic lipase and the lipase of Aspergillus niger catalyze the enantioselective hydrolysis of a series of 4-substituted-2-phenyl-oxazolin-5-ones to yield optically active ()-and ()-N-benzoyl aminoacids respectively.