高效合成氯代苯醌基碳糖苷

报道一种简便、高效的氯代苯醌碳糖苷3a (3b)的合成新方法: 以苯醌基碳苷1a (1b)为原料, 经CH3COCl/THF/H2O体系进行加成反应, 高区域选择性获得糖基间位氯代的氢醌基碳苷2a (2b), 继而通过硝酸铈铵(CAN)氧化得到目标结构3a (3b), 并对所合成的化合物进行了结构表征.     

苯醌在银-汞(膜)微环电极上的循环扫描伏安波

首次报道采用化学镀法制作银－汞（膜）微环电极,并用于探讨苯醌的循环伏安曲线。还对伏安曲线的性质进行了详细的论述。结果表明：苯醌在Ｍｃｌｌｖａｉｎｅ缓冲液中的还原过程属地单电子可逆反应。根据不同扫描速度时还原波的峰电流值可以计算得到苯醌的扩散系数值。     

Semiconducting polymers from triphenylamine derivatives‐benzaldehyde polymers by oxidization with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ)

4‐Tolyldiphenylamine (TDPA) and N,N′‐diphenyl‐N,N′‐bis(4‐methylphenyl)‐1,1′‐biphenyl‐4,4′‐diamine (TPD), were reacted with benzaldehyde (BA) using p‐toluenesulfonic acid as a catalyst to yield linear polymers. The polymers were reacted with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) in tetrahydrofuran (THF) at room temperature. ¹H‐NMR showed that all the methine protons in the residue of BA were completely removed at the mole ratio of repeating unit : DDQ, 2 : 1. The resulting polymers showed good solubility in chloroform or THF. The reacted TDPA‐BA and TPD‐BA polymers gave new UV absorption peaks at 697.0 and 722.5 nm and showed reversible redox potentials about 0.994 and 1.021 V, respectively. Direct current (d.c.) conductivity of the reacted polymers was in the range of 10^?11 S/cm, which is more than two orders higher than the unreacted polymers. The polymer showed pentad split electron spin resonance (ESR) signal, whose concentration was one in 670 or 230 repeating unit for TDPA‐BA and TPD‐BA polymers, respectively. Copyright © 2001 John Wiley & Sons, Ltd.     

Structural,spectroscopic, molecular docking,thermal and DFT studies on metal complexes of bidentate orthoquinone ligand

4‐Triphenylmethyl‐1,2‐benzoquinone (TPMBQ) reacted with some metal ions and the structure of the new compounds had been identified. The metal to ligand ratio was 1:2 which was revealed by elemental analysis. The complexes were found to have octahedral geometry and their thermal stability was studied using thermogravimetric analysis technique. The molar conductance measurements revealed the electrolytic nature of the synthesized chelates. The IR spectra concluded the bidentate nature of the TPMBQ ligand while the ¹H NMR revealed the presence of water molecules. The XRD spectra of Mn (II) and Fe (III) complexes concluded their crystalline structure while Co (II) and Cu (II) chelates refer to amorphous structures. The geometries of the TPMBQ ligand were optimized using Gaussian 09 W; density functional theory B3LYP method. (DFT)/basis set 6–311++G (d, p). HOMO and LUMO energy values for chelates, chemical hardness and electro‐negativity had been calculated. The ligand and its metal complexes had been examined against different kinds of bacteria such as Proteus vulgaris, Escherichia coli, Staphylococcus aurous and Bacillus subtitles to examine their antimicrobial activity. Molecular docking using Auto Dock tools were utilized.     

Total synthesis of reblastatin: convenient preparation of coupling partners and scaled assembly

Potentially scalable total synthesis of reblastatin was achieved based on Panek's previous study. Novel and convenient synthetic routes were developed for the known C8–C20 and C1–C7 coupling partners. The challenging C8–C20 fragment was prepared from TBS protected (S)-5-(hydroxymethyl)dihydrofuran-2(3H)-one (6) in nine steps (20% overall yield), and the C1–C7 fragment was synthesized from commercially available 3,4,6-tri-O-acetyl-d-glucal (9) in eight steps (35% overall yield). On a larger scale, Panek's eight-step assembly of the target molecule from the two partners was also slightly modified, giving 45 mg reblastatin (19% overall yield) in the first batch synthesis. Notable feature of our study is the settlement of the C14 chirality through a diastereoselective α-alkylation of 6 followed by a three-step full reduction of the lactone carboxyl, making vastly available 6 a universally applicable C11–C14 synthon for benzenoid/benzoquinone ansamycins.     

New p-terphenyl and benzoquinone metabolites from the bioluminescent mushroom Neonothopanus nambi

Abstract

Two new p-terphenyls, neonambiterphenyls A and B (1–2), a new benzoquinone, neonambiquinone A (3), together with six known sesquiterpenes (4–9), were isolated from the bioluminescent mushroom Neonothopanus nambi PW3. The isolated compounds were identified by mass, IR and spectroscopic analyses (1D and 2D NMR). Compounds 1–3 and 5–7 showed cytotoxicity against cancer cell lines such as KB, NCI-H187 and MCF-7 with IC₅₀ values ranging from 1.45 to 49.31?µg/mL. In addition, compounds 1 and 5 showed cytotoxicity against Vero cells with IC₅₀ values of 38.72 and 32.90?µg/mL, respectively.     

A combination of in situ ESR and in situ NMR spectroelectrochemistry for mechanistic studies of electrode reactions: the case of p-benzoquinone

A combined in situ NMR and in situ ESR spectroelectrochemical study of a reaction mechanism is presented detecting and describing the whole number of paramagnetic and diamagnetic intermediates and final products in an electrode reaction. While in situ NMR spectroelectrochemistry provides a powerful method for the study of structural or electronic changes of diamagnetic molecules in any electrochemical reaction mechanism, in situ ESR spectroelectrochemistry is the method of choice to detect paramagnetic structures and to characterise their electronic state via the g-value and hyperfine splitting in redox reactions. To demonstrate the power of this combination of magnetic spectroscopies in electrochemistry, the reduction of p-benzoquinone to hydroquinone is followed by both these spectroelectrochemical methods at selected pH values, thus considering the influence of the proton on the reaction mechanism. The results of both in situ spectroelectrochemical methods at the same redox system are used to get the complete reaction mechanism of p-benzoquinone at electrodes in aqueous solutions.     

Crystal Structures and Redox Responses Coupled with Ion Recognition of p‐Benzoquinone‐ and Hydroquinone‐Fused [18]crown‐6

The crystal structures and redox properties of p‐benzoquinone (BQ)‐fused [18]crown‐6 1 and bis‐BQ‐fused [18]crown‐6 2 were examined. The anion radicals of these BQ molecules were stabilized by addition of metal ions, through effective electrostatic interactions between the negatively charged BQ moiety and positively charged ion‐capturing [18]crown‐6 unit. The electrostatic interactions and solvation energy played important roles in determining the magnitudes of anodic redox shifts in the reduction potentials. Regular π‐stacking of BQ units and regular arrays of [18]crown‐6 units were observed in crystal 2 , in which one‐dimensional π‐electron columns were separated by ionic channels. The hydroquinone‐fused [18]crown‐6 molecule 3 and a new BQ‐ and phenol‐fused [18]crown‐6 derivative 4 were obtained as single crystals. The molecular conformations of [18]crown‐6 in crystal 3 and hydrated crystal 3 ?H₂O were different from each other.     

高温红外光谱电化学薄层池的制作与表征

为了拓宽光谱电化学研究范围,开展高温下电化学反应过程,本文研制了一种高温红外光谱电化学薄层池(HTC)。 研制的HTC清洗方便,操作简单,适用于水体系和有机体系。 该HTC可在室温至373 K(根据溶剂沸点,控温精度为±0.5 K)温度范围内使用,具有良好的电化学性能,红外光谱采集谱图清晰信噪比好。 利用铁氰化钾水溶液和对苯醌离子液体溶液的红外光谱电化学行为对HTC进行了表征,得到较满意的结果。     

3,4-去氢-3-羟基-4-苯基-2,5-吡喃二酮的合成

Merck研究小组于1999年报道了一类醌类化合物具有类似胰岛素的作用[1],体内口服给药具有显著的降糖作用,目前在治疗糖尿病方面极具前景。其中3,4 去氢 3 羟基 2,5 吡喃二酮(3)是合成这类醌类化合物的重要中间体。本文报道了该中间体3,4 去氢 3 羟基 4 苯基 2,5 吡喃二酮的合成。合成路线如下图所示。其中化合物的结构均通过熔点、MS、IR、1HNMR确证。1　实验部分1 1　仪器与试剂XRC 1型显微熔点仪测定(温度计未经校正),四川大学科仪厂;Nicolet200SXV傅立叶变换红外光谱仪(石蜡油油湖法),Nicolet公司制造;FinniganLCQDECA型质…