Investigations on the Iron-Catalyzed Asymmetric Sulfide Oxidation
作者:Julien Legros、Carsten Bolm
DOI:10.1002/chem.200400857
日期:2005.2.4
The development of an enantioselective sulfideoxidation involving a chiral iron catalyst and aqueous hydrogen peroxide as oxidant is described. In the presence of a simple carboxylic acid, or a carboxylate salt, the reaction affords sulfoxides with remarkable enantioselectivities (up to 96 % ee) in moderate to good yields. The influence of the structure of the additive on the reaction outcome is reported
Synthesis and catalytic reactivity of D4-symmetric dinorbornabenzene-derived metallotetraarylporphyrins
作者:Ronald L. Halterman、Shyi-Tai Jan、Heather L. Nimmons、David J. Standlee、Masood A. Khan
DOI:10.1016/s0040-4020(97)00729-1
日期:1997.8
D4-symmetry. The resolved benzaldehyde was synthesized in seven steps from p-benzoquinone and cyclopentadiene and included a resolution via diastereomeric ketals. A manganese chloride complex of porphyrin 1 was used as a catalyst for the asymmetric epoxidation of aromatic substituted alkenes in the presence of excess sodiumhypochlorite in up to 7,200 turnovers and up to 76% e.e and >90% yield.
Efficient Asymmetric Oxidation of Sulfides and Kinetic Resolution of Sulfoxides Catalyzed by a Vanadium−Salan System
作者:Jiangtao Sun、Chengjian Zhu、Zhenya Dai、Minghua Yang、Yi Pan、Hongwen Hu
DOI:10.1021/jo040221d
日期:2004.11.1
The asymmetricoxidation of sulfides to chiral sulfoxides with hydrogen peroxide in good yield and high enantioselectivity has been catalyzed very effectively by chiral vanadium−salan [N,N‘-alkyl bis(salicylamine)] complex. The salan ligand shows results superior in terms of reactivity and enantioselectivity to those of salen [N,N‘-alkylene bis(salicylideneimine)] analogue, and provides the sulfoxide
frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal–organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performanceliquidchromatography to separate the enantiomers
Chiral Ionic Liquids as Stationary Phases in Gas Chromatography
作者:Jie Ding、Thomas Welton、Daniel W. Armstrong
DOI:10.1021/ac049144c
日期:2004.11.1
Recently, it has been found that room-temperature ionic liquids can be used as stable, unusual selectivity stationary phases. They show “dual nature” properties, in that they separate nonpolar compounds as if they are nonpolar stationary phases and separate polar compounds as if they are polar stationary phases. Extending ionic liquids to the realm of chiral separations can be done in two ways: (1) a chiral selector can be dissolved in an achiral ionic liquid, or (2) the ionic liquid itself can be chiral. There is a single precedent for the first approach, but nothing has been reported for the second approach. In this work, we present the first enantiomeric separations using chiral ionic liquid stationary phases in gas chromatography. Compounds that have been separated using these ionic liquid chiral selectors include alcohols, diols, sulfoxides, epoxides, and acetylated amines. Because of the synthetic nature of these chiral selectors, the configuration of the stereogenic center can be controlled and altered for mechanistic studies and reversing enantiomeric retention.