通过确定初始电离位点预测吲哚类生物碱质谱的特征裂解规律

确定初始电离位点是EI源质谱解析中一个至关重要的环节. 本文提出了一种确定初始电离位点的新方法. 该法通过计算和分析分子离子自旋密度, 进而比较从中性分子到分子离子的电荷变化和键长变化, 从而确定初始电离位点. 对简单吲哚类生物碱质谱的特征裂解机理进行了预测, 结果与标准物质的质谱吻合. 在此基础上, 与传统的根据基团电离能确定电离位点的方法进行了比较. 结果表明, 该法优于电离能方法. 此法不仅可用于预测以α-裂解为主导的吲哚生物碱和其它含氮化合物的质谱裂解规律, 还为揭示其它小分子化合物以及气相多肽离子的裂解机理奠定了基础.     

单萜吲哚生物碱Uleine及其衍生物的合成进展

生物碱uleine及其衍生物从结构上看属于单萜吲哚生物碱,它们共同的结构特征是吲哚核与碱性氮原子之间只有一个碳相隔,而不像其它单萜吲哚生物碱有两个碳原子.由于其结构特异,天然含量少,因而其合成工作一直吸引着化学工作者.总结uleine生物碱及其衍生物的合成方法,根据构建环的种类不同,把合成方法分为五类.大部分方法都是以吲哚和吡啶衍生物为起始原料进行四环的合成,有几条合成路线简短易行.     

吲哚咔唑类化合物及其衍生物的抗肿瘤活性

吲哚咔唑类化合物是一类提取自微生物发酵液中的生物碱.这一类化合物及其衍生物如staurosporine、ED-110、NB-506、rebeccamycin、氮杂吲哚咔唑、吲哚咔唑糖缀合物和双吲哚马来酰亚胺等,被认为存在广泛的抗肿瘤作用靶点,包括多种与细胞周期有关的激酶、细胞核拓扑异构酶以及与肿瘤细胞生长或凋亡相关的酶等.现已知,吲哚咔唑化合物是拓扑异构酶的致毒剂,其对蛋白激酶的抑制作用表现为竞争结合其ATP口袋上特异的氨基酸基团,从而抑制酶的活性,并引起细胞生长静止于G1期.多年来研究者们努力寻找此类化合物的良好结构,以期得到抗肿瘤活性提高的选择性激酶抑制剂.本文综述了吲哚咔唑类化合物的研究进展、临床应用、抗肿瘤活性产生的机制以及化合物的构效关系(SAR)等.     

3位间接连接有叔胺(仲胺)氮原子的3-季碳氧化吲哚化合物的合成

以3-卤氧化吲哚为起始原料,1,8-二氮杂二环十一碳-7-烯为催化剂,在二氯甲烷中与1-甲基吲哚经取代反应,或在甲苯溶液中于120 ℃条件下与吲哚（吲哚苯环上可连接有取代基）直接发生取代反应,合成了7个3位间接连接有叔胺（仲胺）氮原子的3-季碳氧化吲哚化合物,收率分别为80%~89%和 53%~70%,其结构经¹H NMR, ¹³C NMR和HR-MS（ESI-TOF）表征。     

氮杂吲哚合成

氮杂吲哚是一类重要的杂环分子,在材料科学以及药物设计与合成中具有重要地位。由于氮杂吲哚在结构上区别于吲哚,所以一些经典的合成吲哚的方法并不很适用于氮杂吲哚的合成。近年来,金属有机化学的发展为氮杂吲哚的合成提供了更多的原料选择以及更有效的成环方式,从而为氮杂吲哚的合成开辟了新的方向。本文综述了氮杂吲哚有机合成方法学近年来的进展,介绍了通过Bartoli合成、Fischer吲哚合成、有机锂试剂、过渡金属促进以及其他方法来合成氮杂吲哚类化合物的研究,总结了合成各类氮杂吲哚(4-氮杂吲哚、5-氮杂吲哚、6-氮杂吲哚以及7-氮杂吲哚)的常用有机合成方法,为促进氮杂吲哚类化合物在药物合成化学以及材料科学方面的应用提供了基础。     

2—氧代—3,5,7—三氯吲哚丁酸乙酯的结构分析

为研究吲哚丁酸类氯化物的生理活性，对吲哚丁酸进行酯化、氯化和水解。用高分辨率的质子磁共振谱、质谱和红外光谱、元素分析确证了吲哚丁酸乙酯氯化产物为化合物２－氧代－３，５，７－三氯吲哚丁酸乙酯，该化合物未见文献报道，提出了其生成的可能机理。     

磷酸催化的3-芳基吲哚酮与联烯酰胺的加成反应

3’3-二取代吲哚酮类化合物是一类重要的有机合成中间体,是许多天然生物碱或者药物的结构母核,该类化合物的合成是为近十几年研究的热点之一。3-取代吲哚酮的直接官能化是合成3’3-二取代吲哚酮类化合物常用的方法之一,以3-芳基吲哚酮与联烯酰胺为底物,磷酸为催化剂,室温条件下,通过一步加成反应得3’3-二取代吲哚酮类化合物,收率60%~70%,该反应的原料廉价易得,反应条件温和,经济高效,符合原子经济学的理念。      

催化柴油中含氮化合物类型分布的气相色谱分析方法

建立了催化柴油馏分中各种含氮化合物类型分布的气相色谱-氮化学发光检测分析方法,考察了色谱条件对各种含氮化合物分离的影响。采用Al2O3柱富集催化柴油中的含氮化合物,辅以气相色谱-质谱检测器以及部分含氮化合物标准样品对某催化柴油中的80多个含氮化合物进行了定性(或归类)。以N,N-二甲基苯胺、三丁基胺、喹啉、吲哚、咔唑作为标准样品,考察了各种含氮化合物在氮化学发光检测器上的响应,以吲哚为参照,各含氮化合物的相对响应因子为0.97～1.07,表明含氮化合物的响应与其类型无关。氮的质量浓度在1.0～600 mg/L范围内,含氮化合物的峰面积与质量浓度有良好的线性响应,线性相关系数达0.998。催化柴油中几种含氮化合物(吲哚、C2-吲哚、咔唑、1-甲基咔唑、1,8-二甲基咔唑)含量测定值的相对标准偏差均小于8%。当信噪比(S/N)为3时,测得咔唑氮的检出限为1.0 mg/L。苯胺、喹啉、吲哚、咔唑等4种含氮化合物的加标回收率为89.5%～99.8%。该方法可用于不同来源和不同加工工艺的柴油馏分中各种含氮化合物类型分布的研究。     

无过渡金属催化条件下合成3,3'-二吲哚甲烷衍生物的最新进展（英文）

3,3'-二吲哚甲烷类化合物是一类重要的吲哚生物碱,其结构单元广泛存在于天然产物、功能性材料以及合成药物分子中.因其具有多样的生物活性和功能,如抗氧化、抗炎症、抗血管生成、抗菌以及抗癌活性等,构筑3,3'-二吲哚甲烷类杂环化合物备受关注.传统的合成方法,尤其是对称结构的3,3'-二吲哚甲烷类化合物的合成主要在化学量的Br?nsted酸或Lewis酸存在下,吲哚衍生物与羰基化合物经傅-克反应缩合得到.而过渡金属的使用可引起化合物中金属残留以及环境污染.总结和探讨了从2010年至今3,3'-二吲哚甲烷类化合物的合成方法,尤其是对无过渡金属参与条件下,对称结构的3,3'-二吲哚甲烷类化合物以及非对称结构3,3'-二吲哚甲烷类化合物制备的最新进展以及相应的反应机理,旨在为该类化合物生物活性测试提供重要的理论依据和技术支持.     

对映纯吲(口朶)喹嗪的合成

3-乙酰基-1,4,6,7,12,12b-六氢吲哚[2,3-a]喹嗪(15,16)是吲哚生物碱及羟吲哚生物全合成中用途极广的通用建筑块。合成对映纯的15和16,一直是吲哚生物碱及羟吲哚生物碱全合成中的重要课题。Winterfeldt 首先报道了外消旋体15/16的合成及它与丙二酸二甲酯的高度立体选择性加成。为了改进阿马里新的全合成,Mandal 等1985年再次研究了     

Mass spectral analysis of N-oxides of Chemical Weapons Convention related aminoethanols under electrospray ionization conditions

N,N'-Dialkylaminoethanols are the hydrolyzed products or precursors of chemical warfare agents such as V-agents and nitrogen mustards, and they are prone to undergo oxidation in environmental matrices or during decontamination processes. Consequently, screening of the oxidized products of aminoethanols in aqueous samples is an important task in the verification of chemical weapons convention-related chemicals. Here we report the successful characterization of the N-oxides of N,N'-dialkylaminoethanols, alkyl diethanolamines, and triethanolamine using positive ion electrospray ionization mass spectrometry. The collision-induced dissociation (CID) spectra of the [M+H](+) and [M+Na](+) ions show diagnostic product ions that enable the unambiguous identification of the studied N-oxides, including those of isomeric compounds. The proposed fragmentation pathways are supported by high-resolution mass spectrometry data and product/precursor ion spectra. The CID spectra of [M+H](+) ions included [MH-CH(4)O(2)](+) as the key product ion, in addition to a distinctive alkene loss that allowed us to recognize the alkyl group attached to the nitrogen. The [M+Na](+) ions show characteristic product ions due to the loss of groups (R) attached to nitrogen either as a radical (R) or as a molecule [R+H or (R-H)] after hydrogen migration.     

Interactions of different heterocyclic compounds with monoionic forms of montmorillonite

Interactions of 3-R-and 2-R pyridine (R=CH₃, Cl, NH₂) with Ni(II)-exchanged montmorillonite have been studied. Thermal and X-ray analyses indicate that pyridine derivatives are intercalated into the interlayer spaces of montmorillonite. Infrared spectral data shown that the Lewis and/or Brönsted type of interactions of pyridine derivatives is connected with different steric and inductive effects of the substituents (R) on the pyridine ring. The alkylpyridines increase the electron density on the donor nitrogen atom and support the coordination to the central atom. The halogen substituents have a negative inductive effect (–I), so that those ligands show a lower basicity and weaker σ-bonding properties than pyridine and also the lower possibility of the coordination.     

PHOTOREDUCTION OF PORPHYRINS TO CHLORINS BY TERTIARY AMINES IN THE VISIBLE SPECTRAL RANGE. OPTICAL AND EPR STUDIES

Abstract— The photoreduction of free base porphyrins by tertiary amines in the visible spectral range leads to the formation of chlorin. The increase of the apparent first order rates to yield chlorin is correlated with the inductive effect on the nitrogen of the amine used. A mechanism involving a charge transfer interaction between the photoexcited singlet of the prophyrin and the amine is proposed. The porphyrin radicals formed recombine to form a light sensitive dimer which disproportionates in the dark to yield chlorin and porphyrin. The mechanism is elucidated by the use of EPR, laser and flash photolysis.     

Characterization of fatty acid esters of okadaic acid and related toxins in blue mussels (Mytilus edulis) from Norway

Marine algal toxins of the okadaic acid group can occur as fatty acid esters in blue mussels, and are commonly determined indirectly by transformation to their parent toxins by alkaline hydrolysis. Some data are available regarding the identity of the fatty acid esters, mainly of palmitic acid (16:0) derivatives of okadaic acid (OA), dinophysistoxin-1 (DTX1) and dinophysistoxin-2 (DTX2). Other fatty acid derivatives have been described, but with limited mass spectral data. In this paper, the mass spectral characterization of the [M-H](-) and [M+Na](+) ions of 16 fatty acid derivatives of each of OA, DTX1 and DTX2 is presented. The characteristic fragmentation of [M+Na](+) ions of OA analogues provided a useful tool for identifying these, and has not been described previously. In addition, a set of negative ion multiple reaction monitoring (MRM) methods was developed for direct determination of 16 fatty acid esters of OA, 16 fatty acid esters of DTX1 and 16 fatty acid esters of DTX2 in shellfish extracts. The MRM methods were employed to study the profiles of fatty acid esters of OA analogues in blue mussels and to compare these with fatty acid ester profiles reported for other groups of marine algal toxins.     

Stabilisation of copper(II) tertiary-phosphine or -arsine complexes—II. Role of inductive effect and reaction conditions in stabilising copper(II)-arsine complexes of hybrid oxygen-arsenic ligands from o-R2AsC6H4CO2H

The characterization of the products of reactions between anhydrous/hydrated copper(II) acetate and the title acids having R = Me, C₆H₁₁, Ph and p-tolyl in different solvents and at different temperatures with the help of elemental analysis, TGA, DTA, room temperature magnetic susceptibility, IR, and UV-VIS and EPR spectral data reveal that a competition exists between the chelation of arsine to copper(II) on one side and the reduction of copper(II) to copper(I) and the subsequent chelation of the arsine to copper(I) and/or that of the arsine oxide to copper(II) on the other. This competition which is expected to be normally governed by the inductive effect of group R is disturbed by the change in reaction conditions leading to the conclusion that the reaction conditions rather than the inductive effect of the group R control the mode of reaction.     

Matrix effects of easily ionizable elements and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry

Matrix effects of Na, Ca and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry were investigated with a number of atomic and ionic lines covering a wide range of energies. The plasma was sustained in an Okamoto cavity at atmospheric pressure by using nitrogen as the plasma gas as well as the nebulizer gas. Most of the atomic lines tested exhibited enhancement effects and all of the ionic lines gave suppression effects in the presence of Na and Ca. The effects decreased with increasing microwave power. There was good correlation between matrix effects, the excitation energy and energy sum of the spectral lines. The lower the excitation energy for atomic lines and the higher the energy sum for ionic lines, the stronger the matrix effects. Unlike Na and Ca, nitric acid showed suppression effect for all of the spectral lines and the effect was independent of the energy of the spectral lines and the microwave power. The effect of matrix on the excitation temperature and the electron number density was measured and the mechanism of matrix effect was discussed.     

Optimization of quartz tube pyrolysis atmospheric pressure ionization mass spectrometry for the generation of bacterial biomarkers

Experimental procedures were investigated to improve the efflux of biomolecule pyrolyzates from quartz tube pyrolysis under atmospheric pressure ionization mass spectrometry conditions. Heating regimes, airflows, and ion focusing parameters were optimized to increase the informative mass spectral signals generated from the pyrolysis of Gram-positive bacterial spores and vegetative cells. Dipicolinic acid (DPA) is found in 5-15% by weight in Gram-positive Bacillus spores, and the parameter optimization procedures provided an intense mass spectral signature of the m/z 168 protonated DPA molecule with a minimization of pyrolytic and ionization fragments. Moreover, mass spectral information from the optimization protocols yielded peaks and mass patterns characteristic of DNA and RNA nitrogen bases, protein diketopiperazines, and amino sugars.     

Mass spectral analysis of synthones of nerve agents for verification of the Chemical Weapons Convention

This communication describes the synthesis and gas chromatography/mass spectrometric (GC/MS) analysis of N,N-dialkylphosphoramidic dihalides and alkylphosphonic difluorides, which are synthones of nerve agents. The study was undertaken with a view to developing a spectral database of these compounds for verification purposes of the Chemical Weapons Convention (CWC). The modified synthetic approach reported here has advantages over traditional syntheses in terms of time and yield. GC/MS analysis of these synthones yielded electron ionization (EI) mass spectra and, based on these spectra, generalized fragmentation routes are proposed that rationalize most of the characteristic ions.     

铌酸锂钠钾纳米粉体的溶胶-凝胶法合成及其相转变

采用化学络合法将Nb2O5转化为可溶性铌盐作为铌源, 用溶胶-凝胶法, 在500～650 ℃成功煅烧合成了平均晶粒尺寸为20～60 nm的纯钙钛矿相铌酸锂钠钾[(Li0.06Na0.47K0.47)NbO3]无铅压电陶瓷粉体. 研究了晶粒尺寸对铌酸锂钠钾纳米粉体相结构的影响. 结果表明, 基于纳米尺寸效应, 随着晶粒尺寸由60减小到20 nm, 铌酸锂钠钾粉体的相结构由正交相逐渐过渡到四方相, 而室温下四方相向立方相的转变将发生在20 nm以下.     

Analysis of Trace-Level Volatile Compounds in Fresh Turf Crop （Lolium perenne L.） by Gas Chromatography Quadrupole Time-of-Flight Mass Spectrometry

In the traditional research of volatile compounds, some trace-level compounds could not be identified by gas chromatography-mass spectrometry. Target and post-targeted methods were applied in the investigation of trace-level volatile compounds in fresh turf crop （Lolium perenne L.） based on gas chromatography in combination with hybrid quadrupole time-of-flight mass spectrometry. According to literatures published, a target analysis was performed by using retention index, accurate masses of characteristic ions and second-stage mass spectra （MS2 spectra）. And a series of experiments showed that low electron impact energy was beneficial to the improvement of the abundances of low abundance molecular ion peak. peak was beneficial to qualitative analysis. Totally, 60 Enhancing the abundances of low abundance molecular ion volatile compounds were identified, the great majority cornpounds of which were benzeneacetaldehyde （14.8%）, 2,5-dimethyl-pyrazine （9.6%）, and hexanal （9.3%）. Identification was complied by mass spectral search, retention index and accurate masses of characteristic ions.