Synthesis of Sulfur/Selenium-containing Polyester with Recyclability and Controllable Hydrophilicity and Glass Transition Temperature

We present a ring-opening polymerization of bridged cyclic lactone utilizing alcohol as the initiator and organic base as the catalyst.Bridged γ-butyrolactone monomers(PhSGBL and PhSeGBL) were synthesized efficiently from commercially available 3-cyclohexene-1-carboxylic acid. Due to the ring strain of the bridged structure, ring-opening polymerization of this type of γ-butyrolactone derivative was successfully carried out under mild conditions, e.g., using ethylene glycol as the initiator and a...     

气相色谱法定量分析α－乙酰－γ－丁内酯

 ?Butyrolactone, α-acetyl-γ-butyrolactone and solvent in reaction mixtures from the preparation of α-acetyl-γ-butyrolactone were determined by gas chromatography.The analytes were separated at 190℃ on a 1m ×3mm stainless-steel column packed with silanized 102 white support coated with polydiethylene glycol succinate and monitored with a thermal conductivity detector. The relative error was less than 2.5%.     

Syntheses and Crystal Structures of 12-Oxime Dehydroabietic Acid Derivatives

Three novel dehydroabietate oxime derivatives were synthesized from dehydroabietic acid and their crystal structures were determined by X-ray crystallographic techniques. All of these 12-oxime dehydroabietic acid derivatives crystallize in orthorhombic system, space group P212121. In the structures, rings A and B exhibit chair and half-chair configurations, respectively and form trans ring junction with two methyl groups(C(19) and C(20)) in the axis positions. The oxime groups have E conformations. Comparison of conformations reveals subtle differences principally in ring B due to the modification in C(12). The E-acetaldehyde oxime derivative 2c showed distinct BKα gate-opening activity with an ionic current increase of 164% at 30 μM versus the control current.     

Stereocontrol of the Schiff Base of Substituted Benzaldehyde to Staudinger Cycloaddition Reaction

Syntheses of 4 novel chiral azetidin-2-one derivatives,which were characterized by ^1H NMR,IR,specific rotation and elemental analysis,through Staudinger cycloaddition reaction of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring,were described.For the first time,this type of 3S,4R configuration azetidin-2-one monocrystals with many chiral centers [(3S,4R)-3-hydroxy-N-[(S)-(1-phenyl)ethyl]-4-(2‘‘-chlorophenyl)-azetidin-2-one monocrystal]were obtained,the structures of which were determined by X-ray diffraction analysis.The effects of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring on stereoselectivity of Staudinger cycloaddition reaction products were discussed and the results are showed as below:2-chlorophenyl Schiff base favored to yield 3S,4R configuration product,but 4-chlorophenyl Schiff base favored to yield 3R,4S configuration product.The reaction orientation of 2,4-dichlorophenyl Schiff base was determined by corporate effect of 2- and 4-chlorine,and that of the 4-chlorine was more obvious.In contrast to 4-chlorophenyl,although the main product was 3R,4S configuration,3-chlorophenyl owned lower selectivity.     

CRYSTAL STRUCTURE OF N'- (2-TETRAHYDROF URANYL)- 5-FLUOROURACIL

N'-(2tetrahydrofuranyl)-5-fluorourancil, C_8H_9FN_2O_3,, crystals are triclinic system, a=6.004(2),b=9.022(8),c=16.702(11),α = 99.78(6),β=93.48(3),γ=94.18(6)°. Space group P,Z=4. The diffraction data (Mo K radiation) were collected with Nicolet R3 four-circle diffractometer. The structure was determined by SHELXTL direct methods and refined by least-squares program, R=0.078, Rw=0.069.The structure determination results show that the phase angles of pseudorotation in tetrahydrofuran ring are P=218.6°(mol. 1) and P=177.9°(mol. 2) respectively. Both molecules 1 and 2 arc of the type S[C(6)endo-C(7) exo]. The orientation of the uracil with respect to five-membered ring is positive, x=-53.1 (mol. 1) and x=-18.4(mol. 2).     

Hemislin B Glucoside,a New Lignan from Hemistepta Lyrata

From the ethanolic extract of the whole plant of Hemistepta lyrate Bunge., a new lignan, named hemislin B glucoside,has been isolated and identified as α-(trans-3-methoxy-4-O-β-D-glucopyranosylbenzylidene)-β-(3,4-dimethoxybenzyl)-γ-butyrolactone. Its structure has been established on the basis of UV,IR,FABMS,^1H-NMR,^13C-NMR,HMQC and HMBC spectral analysis.     

Structural Probing on the Sn-C_(C5 ring) Bond of the Sn(Ⅱ) Metallocenes in Both the Solid State and the Temperature-dependent Solution Relaxation State

Various bond modes of the M-C_(C5 ring) exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the C_5 ring.The tin(Ⅱ) metallocene complexes LSn R(L = HC[CMe(N-2,6-iPr_2C_6H_3)]_2,R = cyclopentadienyl,C_5H_5(1); indenyl,C_9H_7(2); fluorenyl,C_(13)H_9(3)) stabilized by the β-diketiminato ligand were prepared and utilized in the study on their solid and solution state structures.X-ray single-crystal diffraction data revealed an η~1-mode of the Sn-C_(C5 ring) bond in each 1~3.However,the room temperature ~1H NMR spectral studies disclosed such a fluxional bonding mode in solution.The 119 Sn NMR studies suggested a quadruple coordination nature of the Sn center in 1 while the triple coordination manner was for the Sn atom in both 2 and 3.Then the variable-temperature(25~–75 ℃) ~1H NMR spectral studies for each 1~3 were performed,which detected the relaxation state structures of 1~3 at lower temperature.All of these results indicate a stereochemical activity of the lone electron pairs at the tin(Ⅱ) atom that definitely has an electronic interaction with the 6 p-electrons of the C_5 ring.The observed Sn-C_(C5 ring) bond modes appear influenced by either the metallocene size or the compound state existed.     

Influence of chelate ring size on the properties of phosphine-sulfonate palladium catalysts

Phosphine-sulfonate based palladium is one of the most extensively studied catalyst systems in olefin polymerization.This type of catalyst features six-membered chelate ring size,and can enable the copolymerizations of ethylene with a wide variety of polar monomers.In this contribution,we decide to investigate the influence of chelate ring size on the properties of phosphinesulfonate palladium catalysts.As such,a series of phosphine-sulfonate ligands and the corresponding seven-membered ring Pd(II)complexes[κ~2-(P,O)-2-(CH_2-PR_1R_2)-4-methylphenyl-sulfonato]Pd(Me)(DMSO)(Pd1,R_1=R_2=Cy,Pd2,R_1=R_2=o-Me O-C_6H_4;Pd3,R_1=Ph,R_2=2-[2,6-(Me O)_2C_6H_3]C_6H_4;DMSO=dimethyl sulfoxide)were designed,prepared and characterized.These palladium complexes are moderately active when they were applied in ethylene polymerization and copolymerizations with methyl acrylate and butyl vinyl ether.However,their properties are greatly reduced from those of the classic six-membered ring phosphine-sulfonate palladium complex Pd2′.The experimental results indicate that the bigger chelate ring size can increase the ligand flexibility and damage the catalytic properties for the phosphine-sulfonate type palladium catalysts.     

Crystal Structure of 5—（l—Menthyloxy）—3—chloro—4— Pyrrolidinyl—2（5H0—f

The molecular structure of the title compound 5-(l-menthyloxy)-3-chloro-4-pyrrolidinyl-2(5H)-furanone, C18H28ClNO3(Ⅰ), has been determined by X-ray diffraction at 296(1)K. The crystal is monoclinic with space group P21, a=9.457(3), b=10.413(3), c=9.525(2), β=95.19(2)°, V=934(1) 3, Z=2, Mr=341.88, Dx=1.22 g/cm3, μ=2.15 cm-1, F(000)=368. The final R factor is 0.059, and Rw is 0.065 for 1020 observed reflections with I≥3σ(I). The absolute configuration at C(14) of the acetal carbon was proved to be S, taking into account the known configuration of 1R, 2S, 5R-menthyl moiety. There are three rings in the molecule of this compound: the furanone ring, the pyrrolidine ring and the mentholoxy group ring. The franone ring is connected with the pyrrolidine ring and the mentholoxy ring by N atom and μ2-O bridge atom respectively.     

Synthesis and Crystal Structure of 5-Allyl-2,3-dihydro-9-（2-hydroxy-5-oxocyclopent-1-enyl）-cyclopenta[b]chromen-1（9H）-one Monohydrate

The title compound 5-allyl-2,3-dihydro-9-(2-hydroxy-5-oxocyclopent-1-enyl)-cyclopenta[b]chromen-1(9H)-one monohydrate(C20H18O4.H2O,Mr = 340.36) was synthesized and crystallized.It crystallizes in the triclinic system,space group P with a = 8.5840(17),b = 8.7027(17),c = 11.561(2),α = 89.69(3),β = 74.33(3),γ = 86.13(3)°,V = 829.6(3)3,Z = 2,Dc = 1.363 g/cm3,MoKa radiation(λ = 0.71073 ),F(000) = 360,μ = 0.098 mm-1,the final R = 0.0430 and wR = 0.1008 for 2957 observed reflections with(I > 2σ(I)).X-ray analysis reveals that atoms C(1),C(2),C(3),C(4),C(5) and O(1) on the new pyran ring are coplanar,which is obviously different from the half-chair or boat conformations of other similar compounds.     

维生素B12环B酰亚胺前体及琥珀胺类药物不对称合成的研究

从γ-丁内酯合成了维生素B₁₂环B酰亚胺前体及琥珀酰胺类药物的3个衍生物,进行了其中不对称季碳的构筑,改进了TiCl₃还原硝基乙烯类化合物的反应,同时发现了一个简便合成乙琥酰胺环的新方法.     

Novel block copolymers of atactic PHB with natural PHA for cardiovascular engineering: Synthesis and characterization

Low-molecular weight macroinitiators derived from natural poly(3-hydroxyalkanoates) (PHAs), which contain olefinic and activated by 18-crown-6 ether carboxylic end groups, were used in anionic ring opening polymerization (ROP) of racemic β-butyrolactone and new diblock copolymers of selected PHAs (PHB, PHBV, PHO) with atactic poly[(R,S)-3-hydroxybutyrate] (a-PHB) were obtained. These novel copolymers were characterized using ¹H NMR, GPC and DSC. Hydrolytic degradation studies of selected copolymers were also performed. Finally, the suitability of these polymeric materials for cardiovascular engineering and as blend compatibilizers was demonstrated.     

红外导数光谱鉴定铁系复合氧化物中γ-Fe2O3

It is well known that γ-Fe_2O_3 is a very active and selective catalyst for okidative dehydrogenation ofbutene to butadiene. It is hard, however, to distingulsh between ferrite spinels and therefore to identify its existence in ferrite-ferric oxide catalysts using XRD. On the IR spectra γ-Fe_2O_3 has characteristic bands in the range of 600~800 cm~(-1), which do not exist for α-Fe_2O_3, Fe3O4, ZnFe_2O_4 and MgFe_2O_4. But these bands are too weak to deterAnne for the small amount of γ-Fe_2O_3, e g. less than 30% (mass fraction), in catalysts.
Usually using second derivative IR spectra can increase the analytical sensitivity substantially. The mechanical mixtures of γ-Fe_2O_3 and MgFe_2O_4 in different ratio were prepared and their second derivative IR spectra were taken. It was found that the bands 730 and 695 cm~(-1) were characteristic of γ-Fe_2O_3 and their intensities increased with the content of γ-Fe_2O_3 in the mixtures. A staight line with R=0.994 can describe the relation between γ-Fe_2O_3 content and the peak area of band 695 cm~(-1). The lowest detectable content of γ-Fe_2O_3 is about 1% (mass fraction). The existence of γ-Fe_2O_3 in the used B-02 comercial catalyst was identified by this method.     

4-羟基脯氨酸立体异构对α-芋螺毒素溶液构象的影响

在α-芋螺毒素及其它家族的芋螺毒素中, 脯氨酸的羟基化是非常普遍的后转录修饰方式. 在天然芋螺毒素中脯氨酸的羟基常采用反式构型, 且该残基对芋螺毒素的结构与生物活性产生了重要的影响, 而顺式构型的羟脯氨酸对α-芋螺毒素的折叠与生物活性的影响还鲜有研究. 本工作通过二维(2D)溶液核磁共振方法测定了经过化学修饰的三个含有反式或顺式羟脯氨酸的α-芋螺毒素的溶液结构, 它们是α4/7亚家族芋螺毒素肽[γ15E]Sr1B、[O7O'/γ15E]Sr1B和[O6O'/γ14E]Vc1A. 研究表明, 羟基顺反异构化学修饰对芋螺毒素的结构影响显著. 羟脯氨酸羟基的反式到顺式修饰导致α-芋螺毒素肽明显的溶液构象变化, 这些变化包括二级结构的改变、关键残基的侧链取向变化以及氢键性质的改变. [O7O'/γ15E]Sr1B与[γ15E]Sr1B相比, 典型的α-芋螺毒素ω弯曲结构发生形变. 而[O6O'/γ14E]Vc1A不同于Vc1A的是末端转角结构的缺失. 本工作加深了对α-芋螺毒素肽的化学修饰法的理解, 该方法是阐明α-芋螺毒素结构-生物活性关系的有用工具.     

水杨醛缩乙二胺双席夫碱及其Ni(Ⅱ) 配合物的电子结构和非线性光学性质的INDO/CI研究

采用量子化学ab initio HF方法, 在6.31G(d)基组水平上， 对水杨醛缩乙二胺类双席夫碱及其Ni配合物体系进行几何构型优化. 以优化的稳定构型为基础, 利用INDO/CI方法计算体系的电子光谱, 同时用ZINDO.SOS方法给出该系列分子二阶(βijk)和三阶(γijkl)非线性光学系数. 计算结果表明, 共轭性增强有助于增大分子的二阶及三阶非线性光学系数, 双席夫碱化合物1的β和γ值分别为35.54×10-30和-1.20×10-34 esu, 而共轭桥为萘环的化合物4的β和γ值分别为54.22×10-30和2.00×10-34 esu, 端部引入苯并环的化合物5的β和γ值增加幅度更大. 对应的金属Ni(Ⅱ)配合物的β值增加较明显, 为配体的1.7~10.8倍, γ值也有不同程度的增加.     

胆固醇修饰富勒烯/γ-环糊精包结复合物的生物活性

采用Bingel-Hirsch反应合成了胆固醇修饰的富勒烯(CHL-C60), 通过核磁共振(NMR)、质谱(MS)、元素分析对CHL-C60的化学结构进行了表征. γ-环糊精(γ-CD)对甾环具有较强的包结能力, 能够与CHL-C60形成包结复合物(CHL-C60/γ-CD), 从而有效提高CHL-C60的水溶性. 紫外-可见吸收光谱和荧光光谱研究结果表明, CHL-C60能够从γ-CD的疏水空腔中解离出来, 与人血清白蛋白(HSA)及牛血清白蛋白(BSA)形成稳定的复合体, 其结合常数分别为5.73×104和7.05×104 L·moL-1. 无氧条件下, CHL-C60/γ-CD通过光诱导电子转移作用断裂pBR322质粒脱氧核糖核酸(DNA), 其效率可达60.5%.     

Herstellung enantiomerenreiner Derivate von 3-Amino- und 3-Mercaptobuttersäure durch SN2-Ringöffnung des β-Lactons und eines 1,3-Dixoanons aus der 3-Hydroxybuttersä ure

Preparation of Enantiomerically Pure Derivatives of 3-Amino- and 3-Mercaptobutanoic Acid by S_N2 Ring Opening of the β-Lactone and a 1,3-Dioxanone Derived from 3-Hydroxybutanoic Acid From (S)-4-methyloxetan-2-one ( 1 ), the β-butyrolactone readily available from the biopolymer ( R )-polyhydroxybutyrate (PHB) and various C, N, O and S nucleophiles, the following compounds are prepared:(s)-2-hydroxy-4-octanone ( 3 ), (R)-3-aminobutanoic acid ( 7 ) and its N-benzyl derivative 5 , (R)-3-azidobutanoic acid ( 6 ) (R)-3-mercaptobutanoic acid ( 10 ), (R)-3-(phenylthio)butanoic acid ( 8 ) and its sulfoxide 9 . The (6R)-2,6-dimethyl-2-ethoxy-1,3-dioxan-4-one ( 4 ) from (R)-3-hydroxybutanoic acid undergoes S^N2 ring opening with benzylamine to give the N-benzyl derivative (ent- 5 ) of (S)-3-aminobutanoic acid in 30?40% yield.     

Diastereoselective total synthesis of 8-epigrosheimin

The first diastereoselective total synthesis of 8-epigrosheimin was accomplished relying entirely on substrate-controlled methods. 8-Epigrosheimin, isolated as an amoebicidal and antibiotic compound from Crepis virens, is a multi-chiral-centered guaianolide with a cis-hydroazulene and a trans-annulated γ-butyrolactone ring. Our approach featured that the γ-butyrolactone unit was formed firstly before the construction of the cycloheptane ring system. The key steps of the synthesis involved (1) a stereoselective Mukaiyama aldol addition; (2) an oxidative γ-lactonization; and (3) an intramolecular aldehyde-ene cyclization.     

A new access to cyclopenta[c]pyridine ring system: syntheses of (−)-plectrodorine and (+)-oxerine

Total syntheses of (−)-plectrodorine [(−)-1] and (+)-oxerine [(+)-3] possessing the cyclopenta[c]pyridine ring system have been accomplished through a route starting from the chiral γ-butyrolactone 7 and exploiting the intramolecular oxazole–olefin Diels–Alder reaction. The sign of specific rotation for the synthetic (+)-3 was in disagreement with that reported for natural oxerine, leaving the absolute configuration of this monoterpene alkaloid incomplete.     

9-羟基苯嵌萘酮的基态能级劈裂的理论研究

当γ,μ满足一定条件时,六次函数V(R,γ)=C[R⁶+2γR⁴+(γ²+μ)R²]的图像是双势阱,可用来描述质子转移,且其相应的Schrodinger方程有解析解.用此势函数结合一维双势阱模型及变分法,并用B3P86密度泛函方法在6-311G水平下计算了该分子的平衡态和过渡态的构型及能量,研究了9-羟基苯嵌萘酮的基态能级劈裂,与其它理论值相比,所得计算结果[Δ_H(0)=86.13cm^-1]与实验值符合得较好.