手性Salen—Co（Ⅱ）配合物催化芳香酮不对称还原反应研究

目前,以廉价的氢气为氢源,由潜手性的酮不对称加氢是制备手性醇最好的方法之一[1].但存在手性催化剂的膦配体不稳定以及贵金属(Ru、 Rh)的流失等问题.硼氢化钠是一种较温和的氢化试剂,Mukaiyama等用具有C2对称轴的一系列光学活性的二亚胺钴配合物催化硼氢化钠不对称还原芳香酮,实现了以硼氢化钠为氢源的不对称氢化反应[2].     

钯催化α-(6-甲氧基-2-萘基)乙醇的不对称羰基化反应

不对称羰基化可产生多种手性分子，而这些手性分子是合成药物和农药等重要前体［１］．光学活性的α－芳基丙酸类如Ｓ－布洛芬和萘普生是很重要的非麻醉性镇痛消炎药．以不对称氢甲酰化反应和氢羧基化反应制备光学活性的布洛芬和萘普生已有报道［２，３］，但这些不对称羰...     

手性助剂诱导下的α,β—不饱和酮的不对称加氢反应及其在合成（R）—…

在ＴＨＦ溶液中，４０－６０℃及０．３－０．５ＭＰａ氢压条件下，「ＲｕＣｌ２（ｃｈｔ）」２＋（Ｓ）－ＢＩＮＡＰ手性催化主本系催化不饱和手性缩酮２选择加氢，再经脱去手性二醇，即可高立体选择地制得（Ｒ）－３－甲基环十五烷酮（４），（Ｒ）－（－）－麝香酮），化学收率≥９５％，     

手性助剂诱导下的α,β-不饱和酮的不对称加氢反应及其在合成(R)-麝香酮中的应用

在ＴＨＦ溶液中，４０－６０℃及０．３－０．５ＭＰａ氢压条件下，［ＲｕＣｌ２（ｃｈｔ）］２＋（Ｓ）－ＢＩＮＡＰ手性催化剂体系催化不饱和手性缩酮２选择加氢，再经脱去手性二醇，即可高立体选择性地制得（Ｒ）－３－甲基环十五烷酮（４，（Ｒ）－（－）－麝香酮），化学收率≥９５％，光学纯度≥９７％．手性缩酮２由Ｄ－苏糖醇或Ｄ－葡萄糖衍生的手性二醇３与３－甲基环十五烯－２－酮１生成．     

新试剂1-(4-安替比林)-3-(4-溴苯基)-三氮烯的合成及其与镉的显色反应研究

新试剂１－（４－安替比林）－３－（４－溴苯基）－三氮烯的合成及其与镉的显色反应研究佘志刚（广东药学院药学系广州５１０２２４）龚楚儒（湖北师范学院化学系黄石４３５００２关键词镉，１－（４－安替比林）－３－（４－溴苯基）－三氮烯，合成，显色反应中图分类号...     

制备分离农药甲霜灵对映体的高效液相色谱法

用高效液相色谱法对自制的纤维素－三（3，5－二甲基苯基氨基甲酸酯）手性制备柱的手性拆分能力进行了评价，并且在此制备柱上完成了对手性农药甲霜灵进行了半制备分离；同时对手性农药甲霜灵在纤维素－三（苯基氨基甲酸酯）、直链淀粉－三（苯基氨基甲酸酯）、纤维素－三（4－甲基苯甲酸酯）手性分析柱上的手性拆分进行了研究。     

(2S,3S,4R)-2-正戊基-3,4-二叠氮基四氢噻吩的合成

以（＋）－4，10－二氧杂三环[5.2.1.O^2,6]－癸－8－烯－3－醇为原料。经8步反应，对映选择性地合成出去氧维生素H的重要中间体：（2S，3S，4R）－2－正戊基－3，4－二叠氮基四氢噻吩。为对映选择性合成手性四氢噻吩类化合物提供了新的方法。     

1-(2-苯并噻唑)-3-(4-偶氮苯基)-三氮烯与汞的显色反应研究及应用

研究了新试剂１－（２－苯并噻唑）－３－（４－偶氮苯基）－三氮烯（ＢＴＰＡＰＴ）与汞的显色反应．在Ｔｗｅｎ－８０存在下，ｐＨ为１１．２０时，Ｈｇ（Ⅱ）与试剂生成红色的１∶１型配合物，最大吸收峰位于５１０ｎｍ，表观摩尔吸光系数为１．１０×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，线性范围０－１４μｇ／２５ｍＬ．建立了可用于饮用水、生活用水和工业废水汞含量测定的方法．     

2-(2-噻唑偶氮)-5-[(N,N-二羧甲基)氨基]苯磺酸与金显色反应研究及其应用

研究了显色剂２－（２－噻唑偶氮）－５－［（Ｎ，Ｎ－二羧甲基）氨基］苯磺酸（简称ＴＡＤＣＡＢＳ）与金（ＩＩ）的显色反应．结果表明，在０．３ｍｏｌ／ＬＨ３ＰＯ４介质中，ＴＡＤＣＡＢＳ与金形成稳定的深红色的３∶１配合物，其最大吸收波长５７５ｎｍ，金浓度在０～５０μｇ／２５ｍＬ范围内符合比耳定律，表观摩尔吸光系数ε５７５为１．４５×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，方法用于测定阳极泥及含硫金矿中微量金，结果满意     

有机溶剂中(R)-醇腈酶催化不对称合成(R)-苯乙醇腈

 研究了来源于杏仁的（R）－醇腈酶在有机溶剂异丙醚中催化苯甲醛与HCN不对称合成（R）－苯乙醇腈，初步探讨了来源于不同杏仁的（R）－醇腈酶的筛选、最适酶量的确定以及底物HCN与苯甲醛的配比、底物浓度、酶的微环境pH和反应温度对不对称合成反应的影响．结果发现，来源于苦杏仁的（R）－醇腈酶优于来源于甜杏仁的（R）－醇腈酶．优化的反应条件为：最适酶量150g／L，HCN与苯甲醛的配比2．5，苯甲醛浓度300mmol／L，酶的微环境pH5．4，反应温度0～5℃．在该优化反应条件下，反应平衡转化率和产物的光学纯度均高达99％以上．     

μ-Azido- and μ-Oxo-Complexes of Fe(III) with Schiff Bases

Two new azido-bridged Fe(III) Schiff base complexes, [Fe(salen)N 3 ] and [Fe(MeO-salen)N 3 ]·2H 2 O, [salen = N , N '-bis-salicylaldehyde(ethylenediimine) and MeO-salen = N , N' -bis-3-methoxysalicylaldehyde(ethylenediimine)] have been synthesized, characterized and studied cryo-magnetically. A new isomeric form of the complex [{Fe(salen) 2 O}] was obtained when attempts were made to grow single crystal of [Fe(salen)N 3 ] from different solvents. The structure of [Fe(salen)] 2 O has been determined by single crystal X-ray analysis. Magnetic susceptibility measurements show the presence of antiferromagnetic interactions in [Fe(salen)N 3 ] and [Fe(MeO-salen)N 3 ]·2H 2 O. The theoretical fit of the susceptibility data yielded values for the spin exchange parameters J = m 10 ( - 0.2) and m 13 ( - 0.3) cm m 1 , for [Fe(salen)N 3 ] and [Fe(MeO-salen)N 3 ]·2H 2 O, respectively.     

离子液体功能化手性salen Mn(Ⅲ)配合物不对称催化仲醇氧化动力学拆分反应

采用共价键联法,将亲水性咪唑类离子液体结构引入手性salen Mn(Ⅲ)配合物的C5位,制备了离子液体功能化手性salen Mn(Ⅲ)配合物.傅里叶变换红外光谱、紫外光谱和旋光分析等结果表明,咪唑类离子液体结构已嫁接到手性salen Mn(Ⅲ)配合物结构中,且嫁接过程未破坏催化活性中心.在以PhI(OAc)2为氧化剂,H2O/CH2Cl2为溶剂的(+/-)-α-甲基苯甲醇不对称氧化动力学拆分反应中,该催化剂表现出比传统手性salen Mn(Ⅲ)催化剂更高的催化活性,仲醇的转化率达到63%以上,对映选择性为99%,拆分效率为18.3%.可通过调变溶剂实现催化剂的分离并重复使用3次以上.实验结果表明,亲水性咪唑离子液体可改善水相反应传质问题且有利于稳定催化活性中间体,从而提高催化活性及稳定性.     

Monodisperse crosslinked pHEMA particle‐supported chiral Mn(III)salen catalyst for asymmetric epoxidation of olefin

Monodisperse crosslinked poly(hydroxyethyl methacrylate) particles (pHEMA) were synthesized for immobilization of the chiral Mn(III)salen homogeneous catalyst by axial coordination. The pHEMA‐Mn(III)salen catalyst was subsequently characterized by FT‐IR, UV and scanning electron microscopy. The results showed that, the heterogeneous Mn(III)salen catalysts also exhibited high activity and enantioselectivity compared to the homogeneous catalyst for the disubstituted cyclic indene and 6‐cyano‐2,2‐dimethylchromene. Moreover, the catalysts were easily separated from the reaction systems and could be renewed several times without significant loss of catalytic activity. Meanwhile, the enantiomeric excess (ee) value remained at 80% in the eighth cycle. The pHEMA support, immobilized by Mn(III)salen, probably acted as a mediator of the reaction between the substrate and the oxidant, and enhanced the stability of the Mn(III)salen compound. Copyright © 2012 John Wiley & Sons, Ltd.     

New chiral (salen)manganese(III) systems for asymmetric epoxidation of styrene

Highly enantioselelctive and repeatable epoxidation of styrene was performed by using new chiral (salen)Mn(III) catalysts, which were derived from the initial immobilization of a homogeneous (salen)Mn(III) complex on solid carriers and subsequent dispersion into ionic liquids. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Complete assignments of NMR data of salens and their cobalt (III) complexes

Salens, derived from 1,2‐ethylenediamine and salicylaldehydes, have been widely used as ligands for metal complexes which have been showing enormous potential in chemical properties of asymmetric catalysts as well as biological properties such as anticancer agents. Almost all of the salen–metal complexes with their corresponding metal (II)‐complexes show the evidences of chelation of two oxygens in salens. However, several metal (II) complexes, especially cobalt (II) complexes, could not show NMR spectra due to their paramagnetism. Recently, it has been reported that one of the cobalt (III) complexes was used for NMR spectroscopy to evaluate its stereoselectivity as a catalyst. Even though many salen ligands are known, their NMR data are not assigned completely. It was possible that modification in northern part of salen with 2‐hydroxyphenyl group afforded another oxygen chelation site in salen ligand. Here we report that synthesis and full NMR assignment of new salen ligands, which form meso 1,2‐bis(2‐hydroxyphenyl)ethylenediamine) and their cobalt (III) complexes. The assignments of ¹H and ¹³C NMR data obtained in this experiment can help us to predict the NMR data of other salen ligands. Copyright © 2008 John Wiley & Sons, Ltd.     

(Salen)Ti(IV) complex catalyzed asymmetric ring-opening of epoxides using dithiophosphorus acid as the nucleophile

A series of chiral bis-Schiff bases were synthesized starting from (1R,2R)-(+)-diaminocyclohexane, (+)-cis-1,2,2-trimethyl-1,3-diaminocyclopentane, (R)-2,2^′-diamino-1,1^′-binaphthalene, and (1S,2S)-diphenyl-1,2-ethanediamine. The enantioselective ring-opening of meso epoxides with dithiophosphorus acids catalyzed by a (salen)Ti(IV) complex formed in situ upon the treatment of Ti(OPr-i)₄ and the aforementioned chiral Schiff base was realized. The resulting products were obtained with low to good enantioselectivities (up to 73% ee). The (salen)Ti(IV) complex containing the backbone of 1,2-diaminocyclohexane exhibited the best enantioselectivity. The substituents in dithiophosphorus acids and those on the salen aromatic ring have a significant influence on the reaction. Moderate enantioselectivity were obtained for the (salen)Ti(IV) complex catalyzed ring-opening of racemic monosubstituted epoxides. High regioselectivity was observed for the alkyl substituted epoxides, whereas poor regioselectivity was obtained for the aryl substituted ones.     

(Salen)tin complexes: syntheses, characterization, crystal structures, and catalytic activity in the formation of propylene carbonate from CO(2) and propylene oxide

A series of (salen)tin(II) and (salen)tin(IV) complexes was synthesized. The (salen)tin(IV) complexes, (salen)SnX(2) (X = Br and I), were prepared in good yields via the direct oxidation reaction of (salen)tin(II) complexes with Br(2) or I(2). (Salen)SnX(2) successfully underwent the anion-exchange reaction with AgOTf (OTf = trifluoromethanesulfonate) to form (salen)Sn(OTf)(2) and (salen)Sn(X)(OTf) (X = Br). The (salen)Sn(OTf)(2) complex was easily converted to any of the dihalide (salen)SnX(2) compounds using halide salts. All complexes were fully characterized by (1)H NMR spectroscopy, mass spectrometry, and elemental analysis, while some were characterized by (13)C, (19)F, and (119)Sn NMR spectroscopy. Several crystal structures of (salen)tin(II) and (salen)tin(IV) were also determined. Finally, both (salen)tin(II) and (salen)tin(IV) complexes were shown to efficiently catalyze the formation of propylene carbonate from propylene oxide and CO(2). Of the series, (3,3',5,5'-Br(4)-salen)SnBr(2), 3i, was found to be the most effective catalyst (TOF = 524 h(-)(1)).     

Macrocyclic Cyclooctene-Supported AlCl–Salen Catalysts for Conjugated Addition Reactions: Effect of Linker and Support Structure on Catalysis

AlCl–salen (salen=N,N′-bis(salicylidene)ethylenediamine dianion) catalysts supported onto macrocyclic oligomeric cyclooctene through linkers of varying length and flexibility have been developed to demonstrate the importance of support architecture on catalyst activity. The role played by the support and the linkers in dictating catalyst activity was found to vary for reactions with contrasting mechanisms, such as the bimetallic cyanide and the monometallic indole addition reactions. While the flexible support significantly enhanced the cyanide addition reaction, most likely by improving salen–salen interactions in the transition state, it lowered the reaction rate for the monometallic indole reaction. For both reactions, significant increase in catalytic activity was observed for catalysts with the longest linkers. The effect of the flexible macrocyclic support on catalysis was further exemplified by the enhanced activity of the supported catalyst in comparison with its unsupported analogue for the conjugate addition of tetrazoles, which is known to be catalyzed by dimeric μ-oxo–salen catalysts. Our studies with the cyclooctene supported AlCl–salen catalysts provides significant insights for rationally designing highly efficient AlCl–salen catalysts for a diverse set of reactions.     

Electropolymerization of Ni(salen) on carbon nanotube carrier as a capacitive material by pulse potentiostatic method

The composites of poly[Ni(salen)] and multi-walled carbon nanotube(MWCNT) were synthesized by pulse potentiostatic method.The composites were characterized by field emission scanning electron microscopy,Fourier transform infrared spectra,and electrochemical impedance spectroscopy.The wrapping of carbon nanotubes with poly[Ni(salen)] varied significantly with anodic pulse duration.Variance of structure of poly[Ni(salen)] caused by anodic pulse duration affected the ability of absorption to solvent molecules or solvated ions,which was indicated by ν(C≡N) intensity.The ability to store/release charge of poly[Ni(salen)] caused by redox switching was evaluated in the form of low-frequency capacitance.Correlations of chargetransfer resistance/ionic diffusion resistance with potential and anodic pulse duration were investigated.     

Transient intermediates from Mn(salen) with sterically hindered mesityl groups: interconversion between MnIV-phenolate and MnIII-phenoxyl radicals as an origin for unique reactivity

In order to reveal structure-reactivity relationships for the high catalytic activity of the epoxidation catalyst Mn(salen), transient intermediates are investigated. Steric hindrance incorporated to the salen ligand enables highly selective generation of three related intermediates, OMnIV(salen), HO-Mn IV(salen), and H2O-MnIII(salen (+*)), each of which is thoroughly characterized using various spectroscopic techniques including UV-vis, electron paramagnetic resonance, resonance Raman, electrospray ionization mass spectrometry, 2H NMR, and X-ray absorption spectroscopy. These intermediates are all one-electron oxidized from the starting MnIII(salen) precursor but differ only in the degree of protonation. However, structural and electronic features are strikingly different: The Mn-O bond length of HO-MnIV(salen) (1.83 A) is considerably longer than that of OMnIV(salen) (1.58 A); the electronic configuration of H2O-MnIII(salen (+*)) is MnIII-phenoxyl radical, while those of OMnIV(salen) and HO-MnIV(salen) are MnIV-phenolate. Among OMnIV(salen), HO-MnIV(salen), and H2O-MnIII(salen (+*)), only the OMnIV(salen) can transfer oxygen to phosphine and sulfide substrates, as well as abstract hydrogen from weak C-H bonds, although the oxidizing power is not enough to epoxidize olefins. The high activity of Mn(salen) is a direct consequence of the favored formation of the reactive OMnIV(salen) state.