高效液相色谱法考察银杏内酯B与其衍生物的变化规律

通过半制备色谱柱从银杏内酯B(GB)中分离出一种衍生物。高效液相色谱结果显示:该衍生物色谱峰的保留时间是GB的3.0倍左右;紫外光谱结果显示:该衍生物的最大紫外吸收波长为212.1 nm,最大吸光值为2.29×104,大约是GB的最大吸光值的100倍,说明是π→π*电子跃迁的结果,表明其分子结构中存在共轭双键;高效液相色谱-质谱分析结果显示:该衍生物在正离子模式下产生的分子离子峰为m/z 429.1(M+Na)+,负离子模式下产生的分子离子峰为m/z 405.2(M-H)-,与GB的分子离子峰质荷比相差18,且与GB具有相似的解离模式。GB对热稳定,而该衍生物对热相对不稳定。pH对两者的关系影响不大,当pH值逐渐增高时,衍生物的开环速度比GB快。溶剂和温度的综合作用对衍生物的稳定性影响更加显著,GB在聚乙二醇溶液中分别于50 ℃下保存15 h和120 ℃下保存4 h后其中的衍生物峰全部消失;将该溶液于120 ℃下保存4 h后分析,除有主峰GB外,在保留时间为1.2～3.0 min范围还伴随有小峰出现,这说明衍生物处于高能态,GB相对较为稳定,两者共存,且相互转化;在特定条件下衍生物能全部转化为GB。     

Synthesis of Some New Heterocycles Derived from Phenylacetyl Isothiocyanate

Phenylacetyl isothiocyanate (1) was reacted with benzoyl hydrazine (2a) in acetonitrile to give thiosemicarbazide derivative 3 which was cyclized by polyphosphoric acid to give 1,2,4-triazoline-5-thione derivative 4. Treatment of 1 with thiosemicarbazide (2b) yielded another 1,2,4-triazoline-5-thione derivative 5. Similar treatment of 1 with phenyl hydrazine (2c) in acetonitrile gave a differently substituted 1,2,4-triazoline-5-thione derivative 6 in one pot-reaction. On the other hand, when the reaction was carried out in acetone, a mixture of 6 and thiadiazolidine derivative 7 was obtained. However, reaction of 1 with hydrazine hydrate (2d) gave hydrazine derivative 8. Reaction of isothiocyanate 1 with anthranilic acid (9) gave benzo[d][1,3,6]oxazin-1-one derivative 10. Treatment of 1 with 2-aminothiophenol (11a), 2-aminophenol (11b) or o-phenylenediamine (11c) produced benzothiazole derivative 12a, benzoxazole derivative 12b and benzimidazole derivative 12c, respectively. The structures of all the products were confirmed by micro-analytical and spectral data.     

Functional monomers and polymers. CXIX.. Synthesis and photochemical reaction of polymethacrylate derivative containing 6-cyanouracil

A polymethacrylate derivative containing 6-cyanouracil was prepared, and its photochemical reaction was studied. The 6-cyanouracil derivative was found to show high reactivity for the photochemiccal reaction. The photochemical-reaction product was identified as a cyclobutanetype photodimer, and the photodimer was formed in high yield even from the monomeric compound of 6-cyanouracil under UV irradiation in low concentration. The quantum yield of the photodimerization of the 6-cyanouracil derivative was greater than that of the thymine derivative. The photodimerization of the 6-cyanouracil derivative could not be quenched by usual triplet quenchers, but was found to be quenched by the polymeric derivative of adenine, suggesting a specific interaction.     

Cyanoacetic acid hydrazide: An efficient access for the synthesis of multi-functional azine and azole derivatives

Herein, the synthesis of nitrogen-containing heterocyclic scaffolds from heterocyclization of cyanoacetic acid hydrazide derivatives is described. Thiosemicarbazide derivative 1a undergoes base-mediated cyclization producing pyrazole derivative of type 2 . The triazolopyridine 5 was obtained by double cyclization of 1a and benzylidene malononitrile. Compound 1b condensed with ethyl chloroformate to furnish pyrazolooxazine 8 . Compound 1b was added to benzoyl isothiocyanate under thermal condition to form oxadiazine derivative 10 while, keeping the above reactant under room temperature to form acyclic derivative 11 . Using CS₂ as a cyclizing agent for compound 1b yielded pyrazole derivative 13 . Treatment of 1b with I₂ resulted in oxidative cyclization producing pyridazine derivative 14 . Compound 1c cyclized with benzoyl isothiocyanate forming triazolothiazine derivative 18 . While using cinnamoyl isothiocyanate, the acyclic product 22 was obtained. Compound 1c was condensed with formaldehyde leading to oxadiazole derivative 25 .     

Aryloxy acetic acid diuretics with uricosuric activity. I. Polycyclic aryloxy acetic acids.

In order to obtain lead compounds for uricosuric diuretics, various polycyclic aryloxy acetic acids [isoindole derivative (7), quinazoline derivative (15), benzopyran derivative (20), xanthone derivative (24), benzofuran derivative (30) and indene derivative (36)] were prepared. These compounds were evaluated for diuretic activity in rats, uricosuric activity in rats and antihypertensive activity in 11-deoxycorticosterone acetate (DOCA)/salt hypertensive rats. Among the compounds, 20 showed potent diuretic, uricosuric and moderate antihypertensive activities. Therefore, we selected 20 as a lead compound for development of new uricosuric diuretics.     

Synthetic Approach Toward Antibiotic Tunicamycins - VII Synthesis of Tunicamine and Tunicaminyl Uracil Derivative

A higher carbon carbohydrate moiety of antibiotic tunica-mycins named tunicamine has been synthesized in a protected form. The key reaction step of the synthesis is a potassium fluoride catalyzed Henry reaction of a 5-nitroribose derivative and a dial do-galactosamine derivative. The tunicamine derivative has been converted to a tunicaminyl uracil derivative by condenation with bis(trimethylsilyl) uracil.     

Synthesis of decahydropyrrolo[2,1,5-cd]indolizine through consecutive [2 + 3] cycloadditions and 6-exo-trig cyclization

Azomethine ylide formed from glycine methyl ester and cinnamaldehyde adds to N-phenylmaleimide to form pyrrolidine derivative, further treatment of which with cinnamaldehyde and N-phenylmaleimide affords the second [2 + 3] cycloaddition adduct, a pyrrolizine derivative with two styrenyl groups at the 3,5-positions. Addition of ICl to the pyrrolizine derivative results in the 6-exo-trig cyclization of the styrenyl groups to form a cycl[3.2.2]azine derivative. The reactions are highly stereoselective affording 11 chiral carbons in three steps. The structure of the cycl[3.2.2]azine derivative was determined by single-crystal X-ray analysis.     

Synthesis, Reactions, and Anti-arrhythmic activity of Substituted Heterocyclic Systems Using 5-Chloroanisic Acid as Starting Material

Summary. A series of substituted heterocyclic systems were prepared from N1-[4-(4-fluorocinnamoyl)phenyl]-5-chloro-2-methoxybenzamide, which was prepared from the corresponding 5-chloroanisic acid (2-methoxy-4-chlorobenzoic acid) as starting material. Treating of the cinnamoyl derivative with hydrazine hydrate in dioxane afforded a pyrazoline, which was reacted with morpholine and paraformaldehyde to give the N-substituted pyrazoline. Acylation of pyrazoline with acetyl chloride in dioxane afforded the N-acetyl analogue. Also, the cinamoyl derivative was reacted with methylhydrazine, phenylhydrazine, or ethyl cyanoacetate to yield the corresponding N-methyl-, N-phenylpyrazoline, pyrane, and pyridone derivatives. Condensation of the cinnamoyl derivative with cyanothioacetamide gave the pyridinethione derivative, which was treated with ethyl chloroacetate affording the ethyl carboxylate derivative. Also, it was reacted with malononitrile or ethyl acetoacetae to give the cyano amino analougues and ethyl carboxylate, which was reacted with methylhydrazine to give the (indazolyl)phenyl derivative. On the other hand, reaction of cinnamoyl derivative with acetyl acetone afforded the cyclohexenyl derivative, which was reacted with hydrazine hydrate to give the [methylindazolyl]phenyl derivative. Condensation of the cinnamoyl derivative with guanidine hydrochloride or thiourea afforded the aminopyrimidine derivative and thioxopyrimidine. The latter was condensed with chloroacetic acid to yield a thiazolopyrimidine, which was condensed with 2-thiophenealdehyde to yield the arylmethylene derivative, however, it was also prepared directly from thiopyrimidine by the action of chloroacetic acid, 2-thiophenealdehyde, and anhydrous sodium acetate. The pharmacological screening showed that many of these compounds have good anti-arrhythmic activity and low toxicity.     

Preparation of Polymeric Membranes Entrapping β-Cyclodextrins and Their Molecular Recognition of Naringin

An amorphous polyetheretherketone known as PEEK-WC and a β-cyclodextrin derivative (O-octyloxycarbonyl-β-CD), insoluble in water, were used to prepare flat sheet membranes by the diffusion induced phase separation. It was found that the β-CD derivative entrapped in membranes is able to form a complex with naringin, a bitter component present in grapefruits. The recognition properties of the β-CD derivative immobilized in the PEEK-WC membranes towards naringin have been investigated as a function of the amount of β-CD derivative present in the casting solution. A significant improvement of the efficiency of theO-octyloxycarbonyl-β-CD was observed when an inclusion complex with naringin in the membrane was formed compared to when the β-CD derivative is dispersed in an aqueous solution of naringin. Washing with an alkaline solution allows an easy regeneration of the membranes and permits their reuse. No recognition properties were found for PEEK-WC membranes made without the β-CD derivative.     

Chemoenzymatic synthesis of an α-substituted serine derivative

An asymmetric synthesis of an α-substituted serine derivative was achieved by employing PLE-catalyzed hydrolysis of a prochiral malonate derivative, and the absolute configuration of the hydrolyzed product was unambiguously determined by the X-ray analysis of a camphorsulfonic acid derivative.     

Synthese von selektiv N- funktionalisierten Polyamin-Derivaten

Synthesis of Selectively N-Functionalized Polyamine Derivatives A threefold differently protected derivative 8 of the triamine spermidine ( 2 ) has been prepared in three steps starting from propane-1,3-diamine ( 1 ). The protected spermidine derivative 8 was converted to its spermine analogue 12 , a useful polyamine intermediate. In a convergent way, the fourfold differently protected derivative 18 of the tetraamine spermine ( 3 ) has been obtained by coupling the two different and separately prepared propane-1,3-diamine units 15 and 17 . Spermidine derivative 19 and spermine derivative 20 , both selectively protected at both primary amino groups, have been Prepared from the free polyamines 2 and 3 , respectively, in a direct approach.     

1,3-Dipolare Addition von 2-Benzonitrilio-2-propanid an 7-Methylthieno[2,3-c]pyridin-1,1-dioxid und Folgereaktionen

1,3-Dipolar Addition of 2-Benzonitrilio-2-propanid to 7-Methylthieno[2,3-c]pyridine 1,1-Dioxide and Subsequent Reactions The addition of dipole 2 , generated photochemically from 2,2-dimethyl-3-phenyl-2H-azirine ( 1 ), to 7-methylthieno[2,3-c]pyridine 1,1-dioxide yields the pyrroline derivative 4 as a major product and regioisomer 5 in low yield. Compound 4 can be transformed into the pyrrolidine derivative 11 by ring opening, loss of SO₂ and hydrogenation. Bromopyrroline derivative 14 gives either by dehydrohalogenation compound 18 or, by substitution, nitrile 17 or ethoxy derivative 19 . Substitution of 14 and ring opening yields methoxypyrrole derivative 20 , which gives access to the unstable hydroxypyrrole and hydroxypyrrolidine derivative 28 resp. 30 . The vinylsulfone 18 is the starting material for addition-ring-cleavage reactions. Oxidation of pyrroline derivative 4 gives epoxy-substituted N-oxide 39 and di-N-oxide 40 ; and oxidative transformation of pyrrolidine derivative 11 yields the (hydroxymethyl)pyridylpyrrolidine derivative 45 .     

Toward hypericin-derived potential photodynamic therapy agents

To optimize a hypericin derivative as a potential photodynamic therapy agent its light-induced singlet oxygen/superoxide radical formation capability should be enhanced and its long-wavelength absorption band should be bathochromically shifted to better match medicinal lasers. A heavy-atom-substituted derivative was realized by electrophilic iodination of hypericin to yield 2,5-diiodo-hypericin. Using photodestruction of bilirubin IX alpha this derivative was demonstrated to exhibit an enhanced light-induced singlet oxygen/superoxide radical formation capability as compared to hypericin. With respect to a bathochromically shifted derivative styryl residues were attached to the methyl groups of hypericin by de novo ring synthesis. Although the long-wavelength absorption band of this derivative displayed a bathochromic shift of nearly 40 nm it unfortunately immediately underwent an intramolecular [2 + 2] cycloaddition to yield the corresponding cyclobutane derivative in which the added conjugation system became interrupted.     

PHOTOCHEMICAL REDUCTION OF 5-BROMOURACIL BY CYSTEINE DERIVATIVES AND COUPLING OF 5-BROMOURACIL TO CYSTINE DERIVATIVES

Irradiation of pH 7, aqueous solutions of 5-bromouracil (BU) in the presence of cysteine peptide-like derivatives at 308 nm using a XeCl excimer laser yielded initial formation of only uracil (U) and the corresponding cystine derivative. Continued irradiation yielded an S-uracilylcysteinyl adduct as well as additional U and cystine derivative. Similar irradiation of a solution of BU and a cystine derivative yielded initial formation of U and the S-uracilylcysteinyl adduct. Formation of these products as well as secondary products of uracil photochemistry was observed upon irradiation of the respective solutions with 254 nm light. With 308 nm laser excitation, U-Cys adduct formation and reduction of BU to U are proposed to occur via initial electron transfer from the disulfide of the cystine derivative to triplet BU. The quantum yield of BU destruction with 308 nm excitation in the presence of cystine derivative is 1.1 X 10(-3). Reaction of triplet BU with the cysteine derivative does not yield U-Cys adduct but U and cystine derivative. A possible byproduct of reduction of triplet BU to U by a cysteinyl residue in a protein BU-DNA complex is a sulphenyl bromide which might yield a protein-DNA crosslink via nucleophilic substitution on sulfur by a nucleophilic site in DNA.     

一种新的改性聚乙二醇毛细管气相色谱固定相

合成了一种新的聚乙二醇衍生物，将其用作毛细管气相色谱固定相，研究了其色谱性能，并成功地分离了二甲苯、氯甲苯、溴甲苯、二氯苯等二取代苯位置异构体；并对其手性分离能力进行了初步研究和讨论。     

Light-energy conversion systems for hydrogen production and photocurrent generation using zinc chlorin derivatives

To develop efficient systems for light-energy conversion, monomeric and dimeric zinc chlorin derivatives were synthesized. These derivatives act as photosensitizers for light-induced hydrogen production with methylviologen as the electron mediator and Pt nanoparticles as the hydrogen-evolution catalyst. The monomeric derivative exhibited ~1.5-times higher activity than the dimeric derivative. The photocurrent-generating activity of the Zn chlorin derivatives assembled on a chemically modified indium tin oxide electrode was investigated; the dimeric derivative exhibited significant activity compared to the monomeric derivative. The photosensitizing activity of the derivatives in dye-sensitized solar cells was also investigated. The dimeric derivative exhibited two-fold higher performance than the monomeric derivative. The dimerization effect on the photosensitizing activities is briefly discussed in terms of stacking conformations based on the results of absorption and fluorescence spectroscopies.     

The use of NMR measurements in the orientation of pyrrolic substitution in 5,6-dihydro-7-methyl-6-oxopyrrolo[1,2a]-[3,1,6]benzothiadiazocine

The title compound 1 , has been shown to give a 1-bromo derivative 2 when subjected to free-radical bromination and a 1-dimethylaminomethyl derivative 3 by reaction under standard Mannich conditions. Vilsmeier formylation, however, furnishes the 3-substituted derivative 4 .     

基于多阶导数拉曼光谱组合技术的矿物油模式分类

为了实现对法庭科学领域重质矿物油物证的快速、准确、无损的鉴定,该文基于光谱分析技术提出了一种多阶导数光谱数据组合分析的方法。收集了80种不同型号、不同厂家的重质矿物油样本,利用傅里叶变换拉曼光谱分析法采集样本的原始光谱数据和导数光谱数据,并通过结合化学计量学构建分类模型。在构建的主成分分析(PCA)结合径向基函数神经网络(RBF)分类模型中,对单独的原始光谱、一阶导数谱和二阶导数谱数据的训练集准确率分别为80.0%、86.7%和86.2%,测试集准确率分别为73.3%、80.0%和72.7%;对组合后的原始光谱+一阶导数谱、原始光谱+二阶导数谱和一阶导数谱+二阶导数谱数据的分类中,训练集准确率分别为97.0%、96.7%和100%,测试集准确率分别为85.7%、90.0%和100%。结果表明,对组合后的导数光谱与原始光谱构建分类模型,准确率更高。其中,基于一阶导数谱+二阶导数谱数据构建的PCA结合RBF分类模型的结果最为理想,准确率达100%。而K最近邻算法模型由于受到样本不均匀的影响,整体分类准确率均较低。利用组合的导数光谱与原始光谱数据构建分类模型能够实现对重质矿物油样本的快速、准确、无损鉴别,可为光谱组合技术在法庭科学及其他分析测试领域的应用提供一定的借鉴和参考。     

Calculation of activation energies using the sinusoidally modulated temperature

Activation energy is calculated from a single curve of a derivative of mass loss perturbed by a sinusoidal modulation of a temperature-time relationship. The method is based on a prediction of a hypothetical derivative of mass loss that corresponds to the absence of this modulation (perturbation). Simple considerations show that the unperturbed derivative coincides with the modulated derivative at inflection points of the modulated temperature-time relationship. The ratio of the perturbed and unperturbed derivatives at the points of time corresponding to maxima and minima of the sinusoidal component of the modulated temperature immediately leads to activation energy. Accuracy of the method grows with decreasing in the amplitude of the modulation. All illustrations are prepared numerically. It makes possible to objectively test the method and to investigate its errors. Two-stage decomposition kinetics with two independent (parallel) reactions is considered as an example. The kinetic parameters are chosen so that the derivative of mass loss would represent two overlapping peaks. The errors are introduced into the modulated derivative by the random-number generator with the normal distribution. Standard deviation for the random allocation of errors is selected with respect to maximum of the derivative. If the maximum of the derivative is observed within the region from 200 to 600°C and the amplitude of the temperature modulation is equal to 5°C, the error in the derivative 0.5% leads to the error in activation energy being equal to 2-6 kJ mol^-1. As the derivative vanishes, the error grows and tends to infinity in the regions of the start and end of decomposition. With the absolute error 0.5% evaluations of activation energy are impossible beyond the region from 5 to 95% of mass loss. This revised version was published online in August 2006 with corrections to the Cover Date.     

Specific recognition of a nucleobase-functionalized poly(3,4-ethylenedioxithiophene) (PEDOT) in aqueous media

In this Letter we report the synthesis, characterization, and electrochemical investigation of a 3,4-ethylenedioxythiophene (EDOT) derivative covalently linked to the nucleobase uracil. The successful electrochemical polymerization of this derivative has provided modified electrodes with a novel functional poly(3,4-ethylenedioxythiophene) derivative. Recognition experiments in aqueous media have shown the specific recognition of the complementary base adenine. The electrochemical detection of the selective binding of nucleobases to this PEDOT derivative in aqueous media can be of particular interest for electrochemical sensor applications in physiological media.