5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇的合成

以5-雄烯二醇为原料,用微生物转化的方法合成了两个重要的神经甾体5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇。所用菌种总枝毛霉为我们自己筛选,并首次应用于5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇的合成中。     

Studies on Hydroiodination and Deconjugation of 5—Aryloxy—（thiophenyl）—3—pentyn—2—one

One-pot hydroiodination and deconjugation of 5-aryloxy(or thiophenyl)-3-pentyn-2-one with a reagent system of sodium iodide/trimethylsilyl chloride/water in acetonitrile at 25℃ have been described.The plasuible mechanism was discussed.The reaction provided a simple and useful method for the preparation of (Z)-β-substituted β，γ-enones and (Z)-β-substituted α，β-unsaturated ketones.     

SmI2－Mediated Addition Reaction of α－Halomethylsulfones to Carbonyl Compounds. A Convenient Synthesis of β－Hydroxysulfones

Due to the chemoselective dehalogenation by SmI2, the addition of a-halomethylsulfones to carbonyl compounds afforded ,β-hydroxysulfones. Those reactions with α-bromomethylsulfones gave the products in moderate to good yields. The SmI2-mediated addition of gem-dihalomethylsulfones to ketones also afforded α-halo-β-hydroxysulfones in moderate yields.     

Structural determination of a new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane from Taxus cuspidata

A new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane were isolated from the methanol extract of the needles of Taxus cuspidata. The structures were established as 2alpha,7beta-diacetoxy-5alpha,10beta,13beta-trihydroxy-2(3 --> 20)abeotaxa-4(20), 11-dien-9-one (1) and 2alpha,5alpha,7beta,9alpha,13alpha-pentahydroxy-10beta-acetoxytaxa-4(20),11-diene (2) on the basis of 1D and 2D NMR spectral data and high-resolution FAB-MS analyses.     

Two isomeric epoxysitosterols from Rhododendron formosanum: 1H and 13C NMR chemical shift assignments

1H and 13C NMR assignments of the two isomeric epoxysitosterols, 5,6 alpha-epoxy-5 alpha-stigmastan-3 beta-ol (1) and 5,6 beta-epoxy-5 beta-stigmastan-3 beta-ol (2), isolated from the leaves of Rhododendron formosanum Hemsl were achieved by 1D and 2D techniques such as DEPT, HMBC, HMQC, COSY and NOESY.     

Highlighting the role of the hydroxyl position on the alkyl spacer of hydroxypropyl-beta-cyclodextrin for enantioseparation in capillary electrophoresis

This work investigates the resolving power of 2,3-dihydroxypropyl-beta-CD (2,3-DHP-beta-CD) and 3-hydroxypropyl-beta-CD (3-HP-beta-CD) as chiral mobile phase additives (CMPAs) using CE. The effects of experimental parameters (CD concentration, buffer pH, and buffer concentration) on enantiorecognition were investigated. More than 20 basic chiral drugs were resolved with satisfactory enantioselectivity. Comparison with 2-hydroxypropyl-beta-CD (2-HP-beta-CD) showed that one or both of the two new chiral selectors show enhanced enantiorecognition for several molecules with bulky substitutes, such as Zopiclone and Mianserin, however, 2-HP-beta-CD has higher enantiorecognition for most of the analytes. Further studies on the structures of analytes and CMPAs showed that the OH moiety on the propyl spacer plays an important role in the separation of some chiral drugs.     

环糊精与两种有机物的包合物的不同光解特性

The effectiveness of the solubilization and photodegradation of β-cyclodextrin （β-CD） and hydroxypropyl-β- cyclodextrin （HPCD） on two hydrophobic organic compounds （HOC） of methyl parathion and pentachlorophenol was investigated. The results indicate that the solubilization or photodegradation of two HOC were influenced by complexing with β-CD or HPCD. The solubility of pentachlorophenol （PCP） was increased linearly with β-CD concentration. The solubility of methyl parathion （MPT） was increased with the increase of β-CD concentration initially, however, as the β-CD concentration was enhanced above 3 g/L, the solubility was decreased with increase of β-CD concentration. The solubilities of two HOC were increased linearly with the increase of HPCD concentration. Although the photodegradation of MPT was improved, the photodegradation of PCP was restrained by complexation of HOC with β-CD or HPCD. In a word, the effectiveness of photodegradation or solubilization of HPCD was more significant than that of β-CD. One potential application of such a method was the in situ remediation of hydrophobic organic pollutants in contaminated soil and groundwater or industrial waste streams.     

Facile Preparation of Homoallyl β′，γ′—Unsaturated Amines via 1,2—Addition of α，β—Unsaturated Imines with Allylsamarium Bromide

A series of homoallyl β′，γ′-unsaturated amines were synthe sized via 1,2-addition of α，β-unsaturated imines with allylsamarium bromide in excellent yields under mild and neutral conditions.     

Selective α-Bromination of β-Keto Esters in Reusable PEG-400 under Mild and Catalyst-free Conditions

An efficient bromination protocol for the synthesis of α-bromo-β-keto esters has been developed. In PEG-400 （poly（ethylene glycol-400））, a variety of β-keto esters were treated with NBS （N-bromosuccinimide） at room temperature to selectively afford the corresponding α-monobromination products in excellent yields. It is noteworthy that the reaction was conducted under mild, environmentally benign and catalyst-free conditions.     

1H and 13C assignments of two new triterpenes from Cladocolea grahami

The structure elucidation and 1H and 13C assignments of the new triterpenes 3beta-palmitoxy-7beta-hydroxyolean-12-ene (1) and its hydrolysis product 3beta,7beta-dihydroxyolean-12-ene (2) and 3beta-sn-glyceroyl-(1'-palmitoxy)urs-12-ene (3), isolated from the aerial parts of Cladocolea grahami (Loranthaceae), are reported.     

过无溶剂、无催化的aza-Michael加成反应合成b氨基酸衍生物

本文报道一种安全,环境有好,经济实用的合成b氨基酸衍生物的新方法。利用α,β不饱和化合物和脂肪族胺,通过无溶剂、无催化的aza-Michael加成反应,高产率的合成b氨基酸衍生物。     

Solvent‐free Thia‐Michael Addition Reactions Using 3‐[Bis(alkylthio)methylene]pentane‐2,4‐diones as Efficient and Odorless Thiol Equivalents

本文研究了3-（二烷硫基甲烯基）-2,4-戊二酮1a 和 1b作为无气味硫醇替代物在无溶剂条件下硫杂麦克尔加成反应中的应用。在浓盐酸作用下,化合物1 发生断键反应, 现场产生的硫醇参与a,b-不饱和羰基化合物2的共轭加成反应,高产率地形成了b-羰基硫醚化合物 3.     

Differences in cytotoxicity of β-sheet peptides originated from silk and amyloid β

The relationships between amino acid sequence, nano-assemblies, and cytotoxicity to neuron cytotoxicity were investigated using β-sheet-forming peptides from Araneus ventricosus spider silk, and amyloid forming peptides Aβ(12-28) (β1), Aβ(28-42) (β2), and full-length Aβ(1-42). Although silk derived peptides formed nano-assemblies, nanofilaments, and nanofibrils with β-sheet contents raging from 24 to 40%, they showed no significant cytotoxicity to neurons. In contrast, nano-assemblies and nanofibrils formed from Aβ peptides with high β-sheet content demonstrated cytotoxicity to the neurons. These differences in cell response between the silk β-sheets and Aβ peptides indicate that the general propensity to form beta sheets and form nanostructures is not sufficient to predict cytotoxicity, while surface charges of the assemblies are significant factors that impact cytotoxicity.     

Synthesis and Characterization of α-Bromo Chalcone Derivatives

α-Bromo chalcones containing 2-thiene ring were prepared in good yields by the condensation of 1-(thien-3-yl)ethanone with aromatic aldehydes, followed by bromination with bromine and selective dehydrobromination with triethyl amine at room temperature.     

Preparative isolation of guaipyridine sesquiterpene alkaloid from Artemisia rupestris L. flowers using high-speed counter-current chromatography

Although the medicinal plant Artemisia rupestris L. has been widely researched for several decades, its alkaloids have never been isolated before. To our surprise, the alkaloids in the plant were not detected in the stems but detected in the flowers. Herein, a novel and strange guaipyridine sesquiterpene alkaloid with a carboxyl group named rupestine was purified successfully from the total alkaloids extracted from the flowers by high-speed counter-current chromatography (HSCCC). The two-phase solvent system used was composed of ethyl acetate-methanol-water (8:1:7, v/v/v). Fifty six milligrams of rupestine was obtained at over 97% purity and 95% recovery from 200 mg of the total alkaloids in one-step separation. Its structure was elucidated by spectroscopic methods including high resolution ESI-MS, (1)H NMR, (13)C NMR, Heteronuclear Multiple Bond Correlation (HMBC), Heteronuclear Single Quantum Coherence (HSQC), and Nuclear Overhauser Enhancement Spectroscopy (NOESY).     

Stereocontrolled Synthesis of (E)-β,γ-Unsaturated Esters via Palladium-Catalyzed Cross-Coupling of (E)-Alkenylboronic Acids with α-Bromoacetic Esters

The cross-coupling reaction of trans-alkenylboronic acids with a-bromoacetic esters was firstly studied. It was found that using Pd(OAc)2 as catalyst, a bulky electron-rich phospine, (2-dicyclohexylphospino-biphenyl) as ligand, the reaction can be readily accomplished to give specific (E)-b,g-unsaturated esters in high yields.     

Three New Diterpenoids from Euphorbia wallichii

Three new abietane diterpene lactones, 3α-hydroxyjolkinolide A (1), ent-8α, 14β-dihydroxy-13(15)-ene-16(12α)-abietanolide (2) and ent-8α,14α-dihydroxy-13(15)-ene-16(12α)-abietanolide (3) as well as a known abietane diterpene jolkinolide A (4) were isolated from the roots of Euphorbia wallichii. Their structures were elucidated on the basis of spectroscopic analysis.     

Veronicafolin－β-环糊精的物化表征及Veronicafolin－羟丙基-β-环糊精包合物溶解性的增强

用氢谱、红外光谱、X-射线粉末衍射、热分析、元素分析等测试方法研究了Veronicafolin (3,5,4′-三羟基-6,7,3′-三甲氧基黄酮) 和β-环糊精 (β-CD) 的固体包合物的谱学特征。元素分析结果显示形成Veronicafolin-β-CD·20H2O包合物，其中C：39.58%, H: 5.75%，表明包合物中主客体比为1∶1。该包合类型属于A_L-型。通过紫外-可见分光光度法研究了在羟丙基-β-环糊精（HP-β-CD）的存在下Veronicafolin的相溶解度曲线，测得校正曲线为y = 24148x + 0.0075 (r=0.9999)，相溶解曲线为y=0.4738x-2.0×10^-7 (r=0.9490)，包结平衡常数Ks为4.5×10⁶mol-1。HP-β-CD提高了黄酮醇Veronicafolin的溶解度。     

Simultaneous separation of eight beta-adrenergic drugs using titanium dioxide nanoparticles as additive in capillary electrophoresis

The analysis is described for separating seven beta-adrenergic blocking agents (atenolol, celiprolol, clorprenaline, fenoterol, metoprolol, propranolol, terbutaline) and clenbuterol (sympathomimetic beta-2 receptor stimulating agonist, decongestant and bronchodilator, illicit anabolic used in athletics) by CE with UV detection. In order to simultaneously separate all analytes, Tris-H3PO4 solution was applied containing titanium dioxide nanoparticles (TiO2 NPs) as BGEs. The effects of important factors, such as concentration of TiO2 NPs, optimum pH, run buffer concentration, and separation voltage, were investigated so as to achieve best CE separation. The eight analytes could be well separated applying a separation voltage of 15 kV in 75 mM Tris-H3PO4 buffer at a pH of 2.40, containing 6.0 x 10(-6) g/mL TiO2 NPs. Under these optimal conditions, the RSDs for peak areas and for migration times were less than 2.7 and 2.3%, respectively. The detection limits were 0.1 microg/mL for celiprolol, 0.1 microg/mL for propranolol, 0.2 microg/mL for fenoterol, 1.0 microg/mL for atenolol, 1.0 microg/mL for clenbuterol, 1.0 microg/mL for clorprenaline, 1.0 microg/mL for metoprolol, and 1.0 microg/mL for terbutaline. The proposed method was successfully applied for the rapid CE determination of the frequently applied antihypertensive beta-blocking compounds atenolol, metoprolol, terbutaline, and propranolol in pharmaceutical tablets.