Synthesis of (2R,3S,4S)-4-aryl-3-hydroxyprolinols

Synthesis of (2R,3S,4S)-4-aryl-3-hydroxyprolinols has been established starting from 2-benzyloxymethylpyrrolidin-2-one framework, which is derived from commercially available trans-(2S,4R)-4-hydroxyproline. The single diastereomer having a trans–cis relative configuration with C₂ and C₃ and C₃ and C₄ is constructed in two one-pot functional group transformations of Grignard addition/dehydration and epoxidation/isomerization as the key steps in moderate yield.     

A new class of peptide chelating agents towards copper(II) ions

Potentiometric and spectroscopic data including CD and EPR results as well as theoretical calculations have shown that the insertion of the tetrazole ring [ψ(CN₄)] in the tetraalanine sequence leads to a very effective peptide chelating agent towards Cu(II) ions. The [ψ(CN₄)] moiety induces a specific peptide conformation which favours the formation of one or two stable chelating rings stabilising a bent structure, with the coordination of 1N-type in CuL or 3N-type in both CuH₋₁L and CuH₋₂L species. It is worth noting that the Cu(II)N_tetr bond does not undergo the hydrolysis process even at high pH although the N_tetr donor is weakly basic.     

新型手性N-烷基-3-蒎胺类化合物的合成及其抑菌活性的研究

以(1S,5S)-(－)-α-蒎烯为原料合成了系列新型(1S,2S,3S,5R)-N-烷基-3-蒎胺类化合物. (－)-α-蒎烯经硼氢化氧化、重铬酸吡啶盐(PDC)氧化得到(1S,2S,5R)-(－)-3-蒎酮; 在BF3•(C2H5)2O催化下(1S,2S,5R)-(－)-3-蒎酮与伯胺化合物反应生成Schiff碱, 再经KBH4或NaBH4还原得到(1S,2S,3S,5R)-N-烷基-3-蒎胺类化合物. 采用FT-IR, 1H NMR, 13C NMR和GC-MS等分析手段对合成所得(1S,2S,5R)-N-烷基-3-蒎烷亚胺和(1S,2S,3S,5R)-N-烷基-3-蒎胺类化合物的结构进行了表征. 考察了(1S,2S,3S,5R)-N-烷基-3-蒎胺类化合物对大肠杆菌(E. coli)、金黄色葡萄球菌(S. aureus)、枯草芽胞杆菌(B. subtilis)、荧光假单胞菌(P. fluorescens)、白色念珠菌(C. albicans)、黑曲霉(A. niger)和米根霉(R. oryzae)等细菌和真菌的抑菌和杀菌活性. 结果表明(1S,2S,3S,5R)-N-正庚基-3-蒎胺对真菌和细菌均表现出良好的杀菌和抑菌活性.     

(R)-TTCA·K催化下环己酮与丙烯腈的加成反应

手性催化剂催化下的不对称合成反应是近年来不对称合成研究中受到重视的领域，如在手性催化剂如，在手性冠醚，手性镧配合物、手性硒、手性铑及手性脯氨酸铷盐等催化下，醛、酮与二烃基锌形成手性醇和不对称羟醛缩合反应等，催化下通过Michael加成反应合成手性化合物的方法近年来也有报道，     

Bis(O-nitrophenyl) Carbonate as a New Reagent for the Synthesis of Chiral Oxazolidin-2-ones

Bis(o-nitrophenyl) carbonate reacts under mild conditions with chirals 1,2-amino alcohols and, after addition of DMAP, affords the corresponding oxazolidin-2-ones in very good yields.     

Complexation of [S,S,S]- and [R,S,R]-isomers of N-bis [2-(1,2-dicarboxyethoxy)ethyl] aspartic acid with Mg(II), Ca(II), Mn(II), Fe(III), Cu(II) and Zn(II) ions in aqueous solution

In a search for environmentally friendly metal chelating ligands for industrial applications, the protonation and complex formation equilibria of [S,S,S]- and [R,S,R]-isomers of N-bis[2-(1,2-dicarboxyethoxy)ethyl] aspartic acid (BCA6) with Mg(II), Ca(II), Mn(II), Fe(III), Cu(II) and Zn(II) ions in aqueous 0.1 M NaCl solution were studied at 25°C by potentiometric titration. The model for complexation and the stability constants of the different complexes were determined for each metal ion using the computer program SUPERQUAD. With all metal ions (M ⁿ⁺), stable ML ^n?6 complexes dominated complex formation for both isomers. Differences in complexation models were found for binuclear species.     

Laser-enhanced ionization and laser-induced atomic fluorescence as element-specific detection methods for gas chromatography. Application to organotin analysis

The applicability of (1R,2R)-1,3-diacetoxy-1-(4-nitrophenyl)-2-propyl isothiocyanate [(R,R)-DANI] as a recently developed chiral derivatizing agent for the enantioseparation of a series of β-blockers is described. The thiourea diastereomers formed were analyzed by reversed-phase high-performance liquid chromatography, mixtures of water and methanol or acetonitrile being used for elution. Conditions of derivatizations (temperature, reagent excess and reaction time) were optimized, and the effects of organic modifiers on the retention and separation were investigated; the diastereomers could readily be baseline separated with methanol-containing mobile phases with resolutions between 1.58 and 2.72.     

A comprehensive approach in perceiving the chelation of Cu(II) and Zn(II) with Alizarin Red S using pH-oscillotitrimetric and volumetric-oscillographic methods

In order to understand the chelation process and investigate the intermediate species as a step towards verifying the exact functional groups that are involved in bonding with transition metals, specifically Cu(II) and Zn(II), pH-oscillotitrimetric (pHOT) and volumetric-oscillographic (VOG) methods have been profoundly used. Alizarin Red S (ARS) - as one of the chameleon compounds (chromogenic) - confirms its different approach of bonding with copper and zinc in different mediums. These two methods thoroughly confirm the adequate conditions for each metal to chelate with ARS. pH is responsible for the ambience in which the formation energy in its less value for the salt or complex to be formed, confirming that pH  =  5 is the value that allows Cu(II) to bond with ARS, whereas Zn(II) bonds at pH = 6. A new approach has been also suggested as to how to discuss the titrimetric curves in both methods, taking into account the importance of ‘volumetric-oscillographs’ that give more information when analysed appropriately. Volumetric-oscillographs have been shown and utilized as fingerprint spectrums to track any change in the solutions and firmly expect the compounds that can be step-by-step formed during titration operation. The resulting-in rules have been suggested during reading the graphs. Moreover, the competition between these two metals to chelate with ARS has been extensively studied.     

Color Reaction Between 4-(2-Pyridylazo)Resorcinol and Mercury (II) in the Presence of Surfactant,and Improved Spectrophotometric Determinations of Mercury(II) and Cyanide Ion with its Coloring

Abstract

The reactions among 4-(2-pyridylazo)resorcinol (PAR), mercury(II) and/or cyanide ion in the presence of water soluble surfactants alone or combination were systematically investigated at about pH 9. The spectrophotometric determinations of mercury(II) and cyanide ion were investigated by using the PAR-mercury(II)-HPC complex (3:2:2 molar ratio) in the presence of N-hexadecylpyridinium chloride (HPC) alone; calibration graphs were rectilinear in the ranges of 0 – 40 μg mercury(II) and 0 –10 μg cyanide ion in a final 10 ml with the apparent molar absorptivities of 5.9 × 10⁴ for mercury(II) and 2.5 × 10⁴ 1 mol^?1 cm^?1 for cyanide ion at 590 nm. The proposed method had advantages—rapidity, simplicity without solvent extraction, and sensitivity in comparison with reported solvent extraction methods. The interference of foreign ions decreased 1/2–l//4-fold compared with that in the presence of non-ionic surfactant alone.     

The Spectropolarimetric Back-Titration of Rhodium(III) with the Chiral Ligand (R,R)-(-)-Trans-1, 2-Cyclohexanediaminetetraacetic Acid

Abstract

Spectropolarimetric back-titrations are described for rhodium(III); the optically active ligand (R, R)-(-)-t?ans-l, 2-cyclohexanediaminetetraacetic acid (R, R(-)CDTA) is used as the complexing agent and cadmium(II) ion as the back-titrant. The optical rotation is monitored throughout the titration, and the optically active ligand and stereospecifically formed complexes serve as self-indicators. The end points are determined graphically by straight-line extrapolations from a plot of volume-corrected observed rotations versus ml of titrant. The rhodium(III) titration plots are representative of normal spectro-polarimetric back-titrations. The range of analyses of rhodium(III) was from 40–0.5 mg.     

Selective Spectrophotometric Determination of Palladium (II) With 2-(5-Bromo-2-Pyridylazo)-5-(Diethylamino)-Phenol

Abstract

A spectrophotometric study of the Pd(II) complex of a reagent 2-(5-Bromo-2-Pyridylazo)-5-(diethylamino)-Phenol (5-Br-PADAP) is presented. A violet complex is formed at pH 3.53, and shows maximal absorbance at 585 nm with molar absorptivity of 3.86 × 10⁴ 1. mol^?1 cm^?1. Beer's law is obeyed up to 50 μ of Pd(II). The method offers the advantages of simplicity, high precision, requires no extraction and is very selective, where 5.0 mg Pt(VI) and 0.3 mg Au(III) ions do not interfere.     

Polarographic Behaviour of Copper Complex with 3-(2′-Thiazolylazo)-2,6-diaminopyridine at Dropping Mercury Electrode

Abstract

The polarographic behaviour of Cu(II) has been investigated in the presence of increasing concentration of 3-(2′-Thiazolylazo)-2,6-Diaminopyridine (2,6-TADAP) at different pH values and in 50% ethanol. At all pH's the waves were found to be diffusion controlled and irreversible. The values of the kinetic parameters n_a, K_o and ? have been evaluated as a function of the ligand concentration. The maximum half-wave potential shifts were observed for the Cu(II) complex at pH 3.37. The polarographic wave height was proportional to the concentration of Cu(II). The method has also been applied to the determination of Cu(II) in aluminium alloys.     

Syntheses,characterizations, crystal structures,and in vitro antitumor activities of chiral triorganotin(IV) complexes containing (S)-(+)-2-(4-isobutyl-phenyl)propionic and (R)-(+)-2-(4-hydroxyphenoxy)propionic acid ligands

Four new chiral triorganotin(IV) carboxylates, [(R₃Sn)(O₂C₁₃H₁₇)] _n (R?=?Me 1, Ph 2), [(R₃Sn)(O₂C₁₃H₁₇)] (R?=?n-Bu 3), and [(R₃Sn)(O₄C₉H₉)] _n (R?=?Me 4), have been synthesized by reaction of (S)-(+)-2-(4-isobutyl-phenyl)propionic acid and (R)-(+)-2-(4hydroxyphenoxy)propionic acid with triorganotin(IV) chloride in the presence of sodium ethoxide. The complexes have been characterized by elemental analyses, FT-IR, NMR (¹H, ¹³C, and ¹¹⁹Sn) spectra, and X-ray crystallography diffraction analyses. Structural analyses show that 1 has a 1-D infinite chiral zigzag chain structure. Complexes 2 and 4 have a 1-D spring-like chiral helical chain with a channel, while 3 is a monomer. Antitumor activities of 1–4 have been studied.     

3-(2-氧代环烷基)丙酸与(R)-2-硫代四氢噻唑-4-羧酸乙酯的反应

３－（２－氧代环烷基）丙酸与（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯的反应李叶芝,田颜清,黄化民（吉林大学化学,长春,１３００２３）关键词（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯,Ｎ－３－（２－氧代环烷基）丙酰－２－硫代四氢噻唑－４－羧酸乙酯,环合反应,...     

2-(2-Thiazolylazo)-p-cresol(TAC) as a Reagent for the Spectrophotometric Determination of Lead(II)

Abstract

The reaction between lead(II) and 2-(2-Thiazolylazo)-p-Cresol(TAC) in the presence of TERGITOL NPX (4 mg/ml) at an apparent pH 9.0–10.0 results in an intensely colored complex which is stable for at least 4 hr.

The composition of the complex is 1:2 cation: TAC and the log of the formation constant is 11.92 ± 0. 40. Beer's law is obeyed up to 6.0μg.ml^?1 of lead(II) at 650nm.

The apparent molar absorptivity at 650 nm is 2.07 × 10⁴ 1. mole^?1.cm^?1 and the detection limit was obtained as 10.0 ng.ml^?1 of lead(II).

The method is applied to determination of lead(II) in copper-base alloy.     

光学活性N-肉桂酰R(S)-4-异丙基四氢噻唑-2-硫酮的合成及其量子化学的研究

用KBH_4,CaCl_2为还原剂使D及L缬氨酸甲酯还原得到光学活性产物R-3-甲基-2-氨基丁醇(2a)及S-3-甲基-2-氨基丁醇(2b)。2a,2b同CS_2在KOH存在下反应得到(R)-4-异丙基四氢噻唑-2-硫酮(3a)及(S)-4-异丙基四氢噻唑-2-硫酮(3b)。肉桂酰氯分别同3a及3b在Et_3N存在下反应得到N-肉桂酰(R)-4-异丙基四氢噻唑-2-硫酮(4a)及N-肉桂酰(S)-4-异丙基四氢噻唑-2-硫酮(4b)。用半经验的量子化学PM3方法研究了反应物和产物的电子结构,得到了产物的最优构型和电荷键序分布以及反应焓变。     

A novel lophine-based fluorescence probe and its binding to human serum albumin

The binding of a lophine-based fluorescence probe, 4-[4-(4-dimethylaminophenyl)-5-phenyl-1H-imidazol-2-yl]benzoic acid methyl ester (DAPIM) with human serum albumin (HSA) was investigated by fluorescence spectroscopy under physiological conditions. While DAPIM shows extreme low fluorescence in aqueous solution, DAPIM binding with HSA emits strong fluorescence at 510 nm. The binding constant and binding number determined by Scatchard plot was 3.65 × 10⁶ M⁻¹ and 1.07, respectively. Competitive binding between DAPIM and other ligands such as warfarin, valproic acid, diazepam and oleic acid, were also studied fluorometrically. The results indicated that the primary binding site of DAPIM to HSA is site II at subdomain IIIA. DAPIM can be a useful fluorescence probe for the characterization of drug-binding sites. In addition to the interaction study, because the fluorescence intensity of DAPIM increased in proportion to HSA concentration, its potential in HSA assay for serum sample was also evaluated.     

光学活性化合物多羟基庚酸乙酯的合成

以不对称环氧化和双羟化反应为构筑手性碳的关键步骤, 首次合成了(＋)-(2R,3S,4S,5S)-6-甲基-4,5-环氧-2,3-二羟基-庚酸乙酯(5)和(－)-(2R,3S,4R,5S)-6-甲基-2,3,4,5-四羟基-庚酸乙酯(11). 找到一条适宜于该类化合物合成的简便有效且立体选择性好的合成路线. 初步生物活性测试表明, 化合物5, 11对HL60细胞具有抑制活性.     

Four Zn(II)/Cd(II)-3-amino-1,2,4-triazolate frameworks constructed by in situ metal/ligand reactions: Structures and fluorescent properties

Four Cd(II) and Zn(II) complexes with the in situ-generated ligand of 3-amino-1,2,4-triazolate (AmTAZ⁻) were isolated from the solvothermal reactions of the corresponding Cd(II) or Zn(II) salts with 5-amino-1H-1,2,4-triazole-3-carboxylic acid (AmTAZAc). Their structures were determined by single-crystal X-ray diffraction analysis. [Zn(AmTAZ)(CH₃COO)] (1) presents a two-dimensional framework constructed from Zn(II) ions and μ₃-AmTAZ⁻ ligands. A remarkable feature of [Zn₄(AmTAZ)₄(SO₄)(OH)(C₂O₄)_0.5]·2H₂O (2) is the construction of the building units of octagonal cylinders which interact with each other by sharing one face or overlapping, resulting in the formation of a three-dimensional framework with three kinds of 1D channels. [Cd(AmTAZ)Br] (3) crystallizes in a chiral space group P2₁2₁2₁, giving a homochiral three-dimensional framework with two types of helical channels (left- and right-handed). Different from the others, the 3-amino-1,2,4-triazole molecules in [Cd(AmTAZH)SO₄] (4) behave as neutral μ₂-2,4-bridges to connect the two-dimensional CdSO₄ sheets into a three-dimensional framework. Of all, 2 and 3 display different fluorescent properties probably due to different metal ions, coordination environments and structural topologies.