Synthesis of Substituted 3H-Indole-modified β-Cyclodextrin

Substituted 3H-indole modified β-cyclodextrin (β-CD) was prepared by the reaction of 6-deoxy-6-[(2-aminoethyl)amino]-β-CD (CDen) with 2-[(p-amino)phenyl]-3, 3-dimethyl-5-car-boxyl-3H-indole (substituted 3H-indole) in the presence of dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt). The product has been characterized by means of elementalanalysis, MS and ^1H NMR.     

Structure determination of glycopeptide of β-momorcharin

The structure of the N-linked oligosaccharide chain of β-momorcharin, a ribosome-inactivating protein from the seeds of Momordica charantia Linn (Cucurbitaceae), was determined. A glycopeptide liberated by pronase digestion of the glycoprotein was subjected to amino acid and neutral carbohydrate analysis to establish the composition of amino acid and sugar residues. The sequences and glycosylation hnkages of the sugar and amino acid residues in the glycopeptide were determined as Manαl-6(XyIβ1-2)-Manβ1-4GlcNAcβ1-4(Fucαl-3)-GlcNAc-Asn-Leu by 2D-NMR spectroscopy and FAB-MS data.     

Silicon mediated synthesis and selected transformations of β-chloroketones

A combination of tetrachlorosilane（TCS） and phenol in dichloromethane was found to be an efficient reagent for hydro-chlorination ofα,β-unsaturated ketones to afford the correspondingβ-chloroketones in good yield at ambient temperature. Reactions of the titled compounds with TCS-NaN₃ as well as with nitriles utilizing TCS-ZnCl₂ to give 1,5-disubstituted tetrazole derivatives orβ-amido ketones respectively are also described.     

Adsorption separation of carbon dioxide, methane, and nitrogen on Hβ and Na-exchanged β-zeolite

Adsorption isotherms of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on Hβ and sodium exchanged β-zeolite (Naβ) were volumetrically measured at 273 and 303 K. The results show that all isotherms were of Brunauer type Ⅰ and well correlated with Langmuir-Freundlich model. After sodium ions exchange, the adsorption amounts of three adsorbates increased, while the increase magnitude of CO2 adsorption capacity was much higher than that of CH4 and N2. The selectivities of CO2 over CH4 and CO2 over N2 enhanced after sodium exchange. Also, the initial heat of adsorption data implied a stronger interaction of CO2 molecules with Na+ ions in Naβ. These results can be attributed to the larger electrostatic interaction of CO2 with extraframework cations in zeolites. However, Naβ showed a decrease in the selectivity of CH4 over N2, which can be ascribed to the moderate affinity of N2 with Naβ. The variation of isosteric heats of adsorption as a function of loading indicates that the adsorption of CO2 in Naβ presents an energetically heterogeneous profile. On the contrary, the adsorption of CH4 was found to be essentially homogeneous, which suggests the dispersion interaction between CH4 and lattice oxygen atoms, and such interaction does not depend on the exchangeable cations of zeolite.     

A Computational Study on Water-assisted Ammonolysis of N-Methyl β-Sultam

IntroductionIt is known that the reactivity and mechanisms ofthe reactions ofβ-sultams with nucleophiles are of in-creasing interest due to the following reasons.1,2-Thi-azetidine1,1-dioxides(β-sultams)are the sulfonyl ana-logues ofβ-lactamantibiotics …     

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.     

Ab initio Study of the Potential Energy Surface and Product Branching Ratios for Reaction of O（^1D） with C2H5CI

The potential energy surface of O（^1D）＋C2H5Cl reaction was studied using QCISD（T）/6- 311＋＋G（d,p）//MP2/6-31G（d,p） method. The calculations reveal an insertion-elimination mechanism. The insertion reaction of O（^1D） and C2H5Cl produces two energy-rich intermediates, IM1 and IM2, which subsequently decompose into various products. The calculations of the branching ratios of various products formed through the two intermediates were carried out using RRKM （Rice-Ramsperger-Kassel-Marcus） theory at the collision energies of 0, 20.9, 41.8, 62.7, 83.6, 104.5, and 125.4 kJ/mol. HCl is the main decomposition product for IM1; CH2OH is the main decomposition product for IM2. Since IM1 is more stable than IM2, HCl is probably the main product of the O（^1D）＋C2H5Cl reaction.     

Extraction and Crystal Structure of β-Sitosterol

The title compound β-sitosterol(C29H50O), an active phytosterol in many medicinal and edible plants, was characterized by X-ray diffraction analysis and extensive nuclear magnetic resonance(NMR) data. It crystallizes in monoclinic system, space group P21 with C29H50O·1/2H2O, a = 9.4226(7), b = 7.4824(9), c = 36.889(3) , V = 2597.0(4) 3, Z = 4, Dx = 1.084 g/cm3, Mr = 423.70, F(000) = 948, and μ = 0.064 mm-1. The final R = 0.0886 and wR = 0.2234 for 10157 observed reflections(I 2σ(I)). The molecular crystal structure of β-sitosterol shows relative stereochemistry of 24R-ethylcholest-5-en-3β-ol. The molecule is composed of one steroid nucleus(3 six-membered rings and 1 five-membered ring) and one sidechain of 10 carbons. There are two C29H50O molecules and one H2O molecule in a symmetrical unit, and the title compound is stacked into a special laminated structure through hydrogen bonds and van der Waal forces. The special laminated structure was first reported.     

Growth of ZSM-5 crystals within hollow β-zeolite

A zeolite composite composed of ZSM-5 andβ-zeolites has been synthesized by a procedure of the nucleation and crystallization of ZSM-5 zeolite in the hollowβ-zeolite.The property ofβ-zeolite crystals with aluminum-poor interior and aluminum-rich outer rim results in silicon extraction favorably in the aluminum-poor bulk rather than the aluminum-rich external surface.Subsequently,alkaline treatment ofβ-zeolite crystals during the second-step synthesis leads to a preferential dissolution of the aluminum-poor center and the formation of hollowβ-zeolite crystals.ZSM-5 zeolite crystals are therefore embedded and grown within the hollowβ-zeolite.The catalytic activities of Co-Hβ,Co-HZSM-5 and Co-HZSM-5/BEA are investigated during the reaction of methane catalytic reduction NO in the presence of O₂.     

Theoretical Studies of Water’s and Methanol’s Effects on Alcoholysis of N-Benzyl-3-oxo-β-sultam

The mechanisms about the water’s and methanol’s effects on the alcoholysis of N-benzyl-3-oxo-β-sultam together with their differences have been studied by using density func- tional theory at the B3LYP/6-31G* level. The results, in comparison with a previous study on the relative reaction without the assistance of water and methanol, show that the added water or methanol can remarkably reduce the energy barrier of alcoholysis reaction of N-benzyl-3-oxo- β-sultam and the most favorite pathway is the breaking of C–N bond instead of S–N. It is also found that the reaction energy barrier of methanol-assisted alcoholysis is a little higher than that of the water-assisted one.     

β沸石的铝化

β沸石自1988年结构被确定以来受到普遍重视,由干结构上的特殊性,G沸石既具有较强酸性又具有明显的碱性［‘,‘］．但q佛石的高硅铝比使其在化学组成上对碱性的贡献甚微,如果能降低其硅铝比,则有可能获得具有较强碱性的佛石分子筛．直接合成的o佛石,硅铝比一般在10以上．     

β-萘甲酰化β-环糊精的分子识别性能研究

最近二十年,外形似“锥简”,腔内疏水,脏外亲水的环糊精（Cyclodextrin,CD包括a,o,7－CD等）,以其特有的结构在模拟酶、分子识别等众多领域内深受广大科学工作者重视［’－‘］．为了获得更有效的模拟酶及分子识别功能体,我们已合成并报道了一系列含有发色基团的CD衍生物卜一句．本文利用基紫外光谱对产一茶甲酸化公CD的分子识别性能作了研究,结果显示3一位修饰CD（3一氧一八茶甲酸基一只CD）1对客体（环己醇）的包结性能是6一位修饰CD（6一氧一界禁甲酸基一八CD）2的4．4倍·结果还显示用环乙烷作客体时与主体正的包结和用…     

Electrochemical synthesis of β-hydroxy-, β-alkoxy-, and β-carbonyloxy sulfones by vicinal difunctionalization of olefins

Disclosed here is an oxidant-free vicinal oxysulfonylation of olefins using electrochemical conditions.     

One-pot Synthesis of α,β-Dehydroamino Derivatives from β,β-Dicyanostyrene with 1,3-Dibromo-5,5-dimethylhydantoin Promoted by Mild Base

The reaction of β,β-dicyanostyrene derivatives(1) with 1,3-dibromo-5,5-dimethylhydantoin(DBDMH) was systematicly studied. The reaction could generate different products when promoted by different mild bases. When the reaction was promoted by NaOAc(100%, molar ratio to compound 1), β,β-dicyanostyrene derivatives could be directly converted into corresponding α,β-dehydroamino derivatives in good to excellent yields in one-pot. When the reaction was promoted by K₃PO₄(80%, molar ratio to compound 1), the corresponding α,β-dehydroamino and double-α,β-dehydroamino compounds were simultaneously obtained and the total conversion of β,β-dicyanostyrene derivatives was up to 90% or higher.     

β-环糊精调控水溶液中Cu2+的辐射还原

在β-环糊精(β-CD)水溶液的安全吸收剂量范围内, 利用β-CD来调控Cu2+的辐射还原. 随着β-CD的加入, 硝酸铜的辐射还原产物从Cu2O 逐渐转变为Cu. 当β-CD浓度增大至8.0 mmol·L-1时, 辐射还原产物主要为Cu纳米粒子. 在辐照过程中, Cu2+的还原没有经历Cu2O的中间过程. 这是由于β-CD对·OH的清除减少了·OH与水化电子(e-aq)的反应, 增大了e-aq的产额, 从而有利于Cu的生成. 另外, β-CD通过羟基在Cu纳米粒子表面的吸附可增强Cu纳米粒子在水溶液中的稳定性. 用紫外-可见(UV-Vis)吸收光谱、粉末X射线衍射(XRD)和选区电子衍射(SAED)对Cu2+辐射还原产物进行了表征.     

Base-catalyzed Formation of Enamines from β,β-Dicyanostyrene Derivatives with N-Bromosaccharin

A new method for the synthesis of functional enamines from β,β-dicyanostyrene derivatives and N-bromosaccharin(NBSA) was developed. In the presence of Na₂CO₃, the the reaction of β,β-dicyanostyrene derivatives with NBSA can generate the corresponding enamines smoothly in a mixed solvent of dichloromethane and N,N-dimethylformamide (DMF)(volume ratio 1:1) at 50℃. The reaction of 14 kinds of β,β-dicyanostyrene derivatives with NBSA was investigated. Screened olefins afforded the corresponding enamines in good to excellent yields(up to 94%), indicating that the method has a wide adaptability for the substrate. The catalyst used is inexpensive and stable for storage. The amino groups of all products in their structures are on the α-position of products, revealing the reaction has an excellent regioselectivity. The possible pathway involving aminobromination of β,β-dicyanostyrene derivative with NBSA first and then elimination of HBr process in one pot has been proposed. The structures of all products were confirmed by ¹H NMR, ¹³C NMR and HRMS analysis.     

β-环糊精及衍生物与β-胡萝卜素包合物性质

为了改善β-胡萝卜素的理化性质,如水溶性和光稳定性等,分别制备了β-胡萝卜素与β-环糊精、2-羟丙基-β-环糊精、磺丁基醚-β-环糊精的固体包合物。利用紫外-可见吸收光谱、傅里叶红外转换光谱和核磁技术对β-胡萝卜素与环糊精及其衍生物的包合物进行研究。通过对包合物理化性质的研究发现:通过β-环糊精、2-羟丙基-β-环糊精、磺丁基醚-β-环糊精包合后的β-胡萝卜素的理化性质,包括热稳定性、光稳定性和抗氧化性,均有显著提高;经2-羟丙基-β-环糊精和磺丁基醚-β-环糊精包合后,β-胡萝卜素分别增溶12倍和18倍。     

α-氯丙酸乙酯对映体与β-环糊精的主客体相互作用

运用量子力学PM3方法模拟α-氯丙酸乙酯((R/S)-ECPA)与β-环糊(β-CD)的主客体相互作用, 探讨(R/S)-ECPA在β-CD上的手性识别机理. 结果表明, (R/S)-ECPA对映体与β-CD形成稳定结合物的结合方式完全不同, (R)-ECPA位于β-CD空腔宽口端, 形成缔合物; (S)-ECPA插入β-CD空腔内形成包结物. 而且, (S)-ECPA与β-CD的结合稳定能低于(R)-ECPA与β-CD的结合稳定能. 在(R/S)-ECPA与β-CD结合物中, (R/S)-ECPA中的手性碳接近葡萄糖单元的C2和C3. (R/S)-ECPA与β-CD之间的手性识别与葡萄糖单元的C2和C3所提供的手性环境和(R/S)-ECPA与β-CD结合的紧密程度密切相关.     

烷基-β-D-吡喃葡萄糖苷的合成与性能

以葡萄糖为原料,经乙酰化、选择性脱C1位乙酰基、转化成三氯乙酰亚胺酯、与受体醇偶联和脱保护5步反应合成了11种不同碳链长度的烷基β-D-吡喃葡萄糖苷。 利用核磁共振、偏光显微镜和热失重分析法对其进行结构表征和性能测试。 结果表明,当烷基β-D-吡喃葡萄糖苷疏水烷基链长n为 6~10时,均具有发泡和乳化性能,特别是正壬基β-D-吡喃葡萄糖苷(n=9)具有更加优异的发泡和乳化性能;当烷基β-D-吡喃葡萄糖苷疏水链的长度n≥7时,均具有热致液晶行为,特别是正十二烷基β-D-吡喃葡萄糖苷(n=12)和十四烷基β-D-吡喃葡萄糖苷(n=14)能够形成更加稳定的液晶态。     

鹰嘴豆β-半乳糖苷酶的分离纯化与表征

从鹰嘴豆中分离得到了三种β－半乳糖苷酶（酶Ⅰ、酶Ⅱ和酶Ⅲ）。将酶Ⅰ和酶Ⅱ进一步纯化,其比活力分别提高了19倍和48倍．酶活力回收率分别为16％和18％,测得它们的表观分子里分别为2．4×104和5.8×104;最适pH分别5.9和5.0,最适温度分别为55℃和45℃．酶Ⅰ水解ONPG和PNPG的KM分别为33×10-2mol·dm-3和60×10-3mol·dm－3;酶Ⅱ水解ONPG和PNPG的KM分别为30×10－3mol·dm－3和60×10－4mol·dm－3.乳糖和半乳糖为该酶的竞争性可逆抑制剂,棉子糖为非竞争性可逆抑制剂．该酶受Hg2＋和PCMB强烈抑制和NEM明显抑制,而Mg2＋、Zn2＋和Ca2＋具有激活作用,推知巯基（－SH)是酶活性中心必须基团．