离子相互作用模型在HCl-LiCl-MgCl2-H2O体系20˚C时溶解度预测中的应用

Component solubility in HCl-LiCl-MgCl2-H2O system of high ionic strength at 20℃ was predicted by using the Pitzer＇s ion-interaction model. The results indicated that the model supplied a very good prediction of the component solubility of the system mentioned above. The values of parameters of β^0, β^1 and C^＊ of HCl, LiCl and MgCl2 were obtained from optimization of literature data, while those of θMN and ψMNX were calculated from a least-squares optimization procedure to couple activity coefficient with solubility data. According to the ion-interaction model, no additional parameters need to be determined for more complex systems. The study provided theoretical basis for the manufacture process, which was proposed by Gao and employed to extract LiCl and MgCl2·6H2O from salt lake brine.     

手性噁唑硼烷催化α-和β-氨基酮不对称还原反应立体选择性的AM1过渡态模型研究

AM1 transition state (TS) models were developed for the enanfioselecfivifies in the reductions of α-and β-aminoketones catalyzed by (S)-4-benzyl-5,5-diphenyl-1,3,2-oxazaborolidine. The result showed that β-aminoketone gave better enanfioselectivity than its α-analog. Different chiralifies of the final products were obtained, R for the former and S for the latter. These semiempirical TS models are consistent with the experimental data.     

Synthesis of 2,15-Hexadecanedione as a Precursor of Muscone

Muscone is a precious fragrant compound scarce in nature. Many synthetic attempts for this unique natural product have been carried out. In this work, the one-carbon unit transfer reaction of tetrahydrofolate coenzyme was initialed. Bisbenzimidazolium salt was used as tetrahydrofolate coenzyme model, and thus the biomimetic synthesis of 2,15-hexadecanedione, a precursor of muscone, was successfully accomplished by using the addition-hydrolysis reaction of bisbenzimidazolium salt with methyl magnesium iodide.     

Novel Phenomenon of Oxygen-to-oxygen Silyl Migration in Directed Aldol Reaction

The phenomenon of migration of the silyl groups from α-oxygen to β-oxygen in sodium aldol reaction was observed for the first time in this paper.     

Kinetics of Catalytic Hydrolysis of Potato Starch by Immobilized β-Amylase

The enzyme activity of immobilized β-amylase carried on active carbon and the reaction kinetics for hydrolysis of potatostarch catalyzed by the enzyme have been investigated. A kinetics model based on the overall reaction has been suggested and a reaction coefficient as a new parameter introduced. All of the kinetics parameters involved in the model, including the reaction coefficient, reaction order rate constant as well as the maximum reaction rate etc. at different temperatures have been obtained by using the modified Quasi-Newton optimization technique.     

The Triangle-relationship of β-lactam Antitiotics

The geometric parameters for D-Ala-D-Ala are optimized by MM, the most and next two stable conformations are obtained. According to the interaction model with target emzyme suggested by us, the traingle-relationship of it is obtained. This triangle-relationship could be found in the pharmaceuticals belong to different classes of β-actams also.     

Optimized Separation of Pharmacologically Active Xanthones from Secuidaca inappendiculata by Capillary Electrophoresis

A capillary electrophoresis (CE) method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically optimized with respect to pH, concentration of running buffers,addition of sulfated β-CD,applied voltage and column temperature.Baseline separation was achieved for the nine xanthones in less than 15 minutes using a background electrolyte consisting of 200 mmol/L borate (pH9.5) and 10 mmol/L sulfated β-CD.     

Synthesis and Liquid Crystalline Properties of 3-Substituted Pentane-2,4-dione, Pyrazole and Isoxazole Derivatives

The γ-substituted β-diketonate 2,4-dioxo-3-pentyl 4-[4-（n-octyloxy）cinnamoyl]oxybenzoate 1 and its pyrazole and isoxazole derivatives （2 and 3 respectively） have been synthesized and characterized by the spectroscopic methods and elemental analysis. The mesogenic properties of these compounds have been studied by polarizing optical microscopy （POM） and differential scanning calorimetry （DSC）. A monotropic nematic mesophase was observed for the β-diketonate 1, in contrast, the pyrazole 2 displays an enantiotropic smectic A and isoxazole 3 exhibits an enantiotropic nematic mesophase. The relationship between the structure and liquid crystalline properties has also been discussed.     

Synthesis of Novel C2-Symmetrical Bidentate Phosphoramidite Ligands for Rh-catalyzed Asymmetric Hydrogenation of β-（Acylamino）acrylates

Enantiomerically pure β-amino acids and their derivatives are especially attractive due to their vital importance for biochemical and medicinal applications1. One of the most convenient paths to β-amino acids involves the asymmetric hydrogenation of the…     

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。     

Fragmentation Mechanism of Trans—α—Aryl—β—enamino Esters

Electron impact-induced fragmentation mechanism of Trans-α-Aryl-β-enamino esters were investigated using mass-analyzed ion kinetic energy (MIKE) spectrometry and high resolution accurate mass data It was found that the main characteristic fragmentations of compounds studied were:an odd electron ion M^ -EtOH was formed by losing a neutral molecule of ethanol;and the skeletal rearrangements took place;and the ring opening reaction happened after losing a carbon monoxide;and the typical McLafferty rearrangement underwent in ester group.The cycliztion reation caused by losing neutral molecule of TsNH2 due to the ortho-effects of substituted group of gromatic ring was also observed.     

胆甾-4α-甲基-8-烯-3β，7α-二醇二乙酸酯的结构与性质研究

Lophenol, cholest-4α-methyl-7-en-3β-ol (1), obtained from Dracaena cochinchinensis (Lour.) S. C. Chen, was structurally modified. It was acetylated to protect 3β-hydroxyl group, and then oxidised by selenium dioxide in acetic acid to give cholest-4a-methyl-8-en-3β, Ta-diol diacetate (3). This compound 3 is unstable in chloroform solution or when heated and easily converted to a diene compound, cholest-4a-methyl-7,14-dien-3β-ol acetate (4). The structures of 3 and 4 were elucidated by means of IR, ^1H NMR, ^13C NMR and MS, and the absolute configuration of 3 was established by X-ray crystallography. The property of 3 was also discussed in this paper. Both 3 and 4 are new compounds and were reported for the first time.     

Studies on the Mass Spectra of N‐Aryl α,β‐Unsaturated γ‐Lactams

The mass spectra of a series of N‐aryl α,β‐unsaturated γ‐lactams were studied. Besides the molecular ion, the three characteristic fragments such as [M⁺‐29], [M⁺‐55], and [M⁺‐82] were commonly found in a series of N‐Aryl α,β‐unsaturated γ‐lactams in EI/MS. Further more the mechanism for the interpretation of these fragments is also de scribed.     

Diastereoselective Coupling of N‐(tert‐Butyl)sulfinyl Imines and Dimethyl Malonate. Synthesis of Enantiomerically Enriched β‐Amino Esters and β‐Lactams

A diastereoselective coupling of dimethyl malonate with N‐(tert‐butyl)sulfinyl imines under solvent‐free conditions was developed, using NaHCO₃ or NaI as base promoters. The resulting dimethyl 2‐(1‐aminoalkyl)malonates could be easily transformed successively to β‐amino esters and the corresponding β‐lactams with high optical purity.     

Microwave‐Assisted Synthesis of β‐Lactams and Cyclo‐β‐dipeptides

Different cyclo‐β‐dipeptides were prepared from corresponding N‐substituted β‐alanine derivatives under mild conditions using PhPOCl₂ as activating agent in benzene and Et₃N as base. To evaluate β³‐substituent influence, the amino acids 7 – 26 were synthesized, and a β‐lactam formation reaction was carried out instead of cyclo‐β‐dipeptide formation. The crystal structures of three derivatives of cyclo‐β‐peptides and one β‐lactam are presented.     

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.     

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。     

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。     

An Efficient One-pot Synthesis of β-Amino/β-Acetamido Carbonyl Compounds via ZrCl4-catalyzed Mannich-type Reaction

Zirconium(IV) chloride catalyzed efficient one-pot synthesis of β-amino/β-acetamido carbonyl compounds at room temperature is described. In the presence of ZrCl4, the three-component Mannich-type reaction via a variety of in situ generated aldimines, with various ketones, aromatic aldehydes and aromatic amines in ethanol, led to the formation of β-amino carbonyl compounds and the four-component Mannich-type reaction of aromatic aldehydes with various ketones, acetonitrile and acetyl chloride resulted in the corresponding β-acetamido carbonyl compounds in high to excellent yields. This methodology has also been applied towards the synthesis of dimeric β-amino/β-acetamido carbonyl compounds.