Analysis of flavonoid constituents from leaves of Acanthopanax senticosus harms by electrospray tandem mass spectrometry

Three known flavonoids, quercetin, quercitrin (quercetin-3-0-rhamnoside) and rutin (quercetin-3-0 rutinoside), have been identified for the first time in the leaves of Acanthopanax senticosus Harms by using electrospray tandem mass spectrometry techniques (ESI-MS(n)). The flavonoid hyperin (quercetin-3-0-beta-galactoside), already known to be present, was also investigated. The diagnostic fragment ions of the aglycone quercetin were obtained in the ESI-MS(n) experiments, and a fragmentation mechanism proposed.     

Pd-catalyzed aerobic oxidative coupling of anilides with olefins through regioselective C-H bond activation

Pd-catalyzed aerobic oxidative coupling of anilides with olefins was achieved through selective C-H bond activation. Compared to the previous studies, not only did we successfully use molecular oxygen to replace the chemical oxidant, but we also obtained improved yields for a number of substrates. The reaction tended to give high yields for electron-rich anilides and electron-deficient olefins, with a best yield up to 91%.     

用CR传输线模型研究涂层/金属体系阻抗谱

根据CR传输线模型和QR电路之间的关系,建立了拟合其初值的计算方法,借助Z-View软件,可求得各元件精确值.根据电容（Ci）和电阻（Ri）随特征频率（f*）的分布,推导了元件相对增量与恒相位角元件（Q）指数参数n的关系. 结果表明, 当n小于0.5时,Ci比Ri增加得更快,从新的角度说明了n的物理意义及其和界面脱层之间的关系.作为应用实例,拟合了不同特征的电化学阻抗谱,分析了有机涂层/金属腐蚀体系阻抗变化的具体过程,区分了点蚀和脱层因素对阻抗谱的影响,从高阻抗体系同时得到了与不同空隙率有关的涂层电容和电阻值,并根据涂层体系的不均匀特征探讨了模型结构的物理意义.     

F-T合成Fe/Cu/K/Al2O3催化剂的结构性质、还原及碳化行为

采用连续共沉淀与喷雾干燥成型技术相结合的方法制备了微球状Fe/Cu/K/Al2O3催化剂, 结合TG、N2物理吸附、XRD、H2-TPR、CO-TPR、Mossbauer谱等表征手段, 研究焙烧温度对Fischer-Tropshc (F-T)合成铁基催化剂的结构性质、还原行为和碳化行为的影响. 结果表明, 较高的焙烧温度有利于碳酸盐的分解和结晶水的脱除, 促进了催化剂的还原. 随着焙烧温度的进一步升高, 催化剂的比表面积减小, 平均孔径增大, α-Fe2O3晶粒的粒径增大, 催化剂中金属与载体的相互作用增强, 从而削弱了CuO、K2O助剂的作用, 严重抑制了催化剂的还原和碳化.     

硫杂杯-1,3-2,4-氮杂双冠醚的合成与氨基酸配合性能

对叔丁基硫杂杯四酰肼衍生物(2)与邻苯二甲醛发生分子内1+2缩合反应, 合成了首例1,3-交替构象的硫杂杯-1,3-2,4-氮杂双冠醚(3), 产率为65%. 其结构经元素分析、质谱、核磁共振谱等表征证实. 用UV-Vis光谱法和1H NMR谱研究了化合物3与系列α-氨基酸的识别配合性能, 并计算出其配合常数. 结果表明, 主体分子3对所测试的α-氨基酸有较好的配合作用, 主客体分子形成1∶1的配合物.     

Unusual regioselectivity of Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with allenic/propargylic zinc reagents. Highly selective synthesis of 6-phenylhex-5-yn-2(or 3)-enoates/enitrile and 4-phenyl-6-substituted-hexa-2,4,5-trienoates

The Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with the organozinc formed by the subsequent treatment of 1-phenylalk-1-yne with n-BuLi and ZnBr2 with or without a catalytic amount of HgCl2 was studied. Both the allene-formation- and the alkyne-formation-type coupling reactions were observed with high regio- and stereoselectivity: the reaction of 1-phenylprop-1-yne afforded 6-phenylhex-5-yn-2(or 3)-enoates and -enitriles, while the reaction of 1-phenylhex-1-yne formed 4-phenyl-6-substituted-hexa-2,4,5-trienoates. A plausible explanation for the regioselectivity was discussed. The double bonds in 6-phenylhex-5-yn- 2-enoates were prone to migrate to the position conjugated with the carbon-carbon triple bonds to form 6-phenylhex-5-yn-3-enoates at higher temperature. The migration did not occur in absence of an excess amount of allenic/propargylic zinc reagent or at low temperature.     

富氧条件下乙炔选择催化还原NOx

Acetylene as a reducing agent of metal exchanged HY catalysts, for selective catalytic reduction of NO in the reaction system of 0.16% NO, 0 （C2H2-SCR） was investigated over a series 08% C2H2, and 9.95% O2 （volume percent） in He. 75% of NO conversion to N2 with hydrocarbon efficiency about 1.5 was achieved over a Ce-HY catalyst around 300 ℃. The NO removal level was comparable with that of selective catalytic reduction of NOx by C3H6 reported in literatures, although only one third of the reducing agent in carbon moles was used in the C2H2-SCR of NO. The protons in zeolite were crucial to the C2H2-SCR of NO, and the performance of HY in the reaction was significantly promoted by cerium incorporation into the zeolite. NO2 was proposed to be the intermediate of NO reduction to N2, and the oxidation of NO to NO2 was rate-determining step of the C2H2-SCR of NO over Ce-HY. The suggestion was well supported by the results of the NO oxidation with O2, and the C2H2 consumption under the conditions in the presence or absence of NO.     

New Stephaoxocane Alkaloids from Stephania longa

Three new stephaoxocane‐type alkaloids, stephalonganines A–C ( 1 – 3 ), together with the known eletefine ( 4 ), were isolated from the whole plant of Stephania longa. Their structures were fully characterized spectroscopically, and the absolute configurations of the new alkaloids were assigned by comparison of their circular‐dichroism (CD) data with those of 1,2‐dihydrostephaoxocanine ( 5 ), in combination with 2D‐NMR experiments.     

Analysis of bufadienolides in the Chinese drug ChanSu by high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry

The qualitative analysis of bufadienolides in the Chinese drug ChanSu was performed using high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS). Bufadienolides are the major bioactive constituents of ChanSu, which is used to treat heart failure and cancer in traditional Chinese medicine. The APCI-MS fragmentation behavior of bufadienolides was studied. For bufadienolides with only hydroxyl substituents, the fragmentation was characterized by successive eliminations of H(2)O and CO molecules, and the profile of MS/MS product ions was correlated with the number of hydroxyl groups. If a C-16 acetoxyl group was present, the fragmentation of [M+H](+) ions was triggered by initial loss of 60 Da (HOAc). The elimination of CO was significant for bufadienolides with a 19-formyl group, and the 19-hydroxyl group could be characterized by the loss of 30 Da (HCHO). These fragmentation rules were applied to the identification of bufadienolides in a methanolic extract of ChanSu, which was separated on a C(18) column with gradient elution. A total of 35 bufadienolides were identified, including four new constituents. The method established here facilitated the convenient and rapid quality control of ChanSu crude drug and its pharmaceutical preparations.     

Azinoiminophosphorane mediated synthesis of 5H, 7H‐1,2,4‐triazolo[1,5‐c][1,3]benzoxazepin‐7‐ones and 6H,8H‐1,2,4‐triazolo‐[1,5‐c][1,3]oxazepin‐6‐ones

The aza‐Wittig reactions of benzophenone‐, acetophenone‐ and benzaldehyde l‐[(triphenylphosphoranyl‐idene)amino]ethylidenehydrazones (4) with phthalic anhydride, 2,3‐dimethylmaleic anhydride and 7‐oxabi‐cyclo[2,2,l]hept‐5‐ene‐2,3‐dicarboxylic anhydride ( 5a ) provide a new route to 5H,7H‐1,2,4‐triazolo[1,5‐c]‐[1,3]benzoxazepin‐7‐ones 8a‐c or 6H,8H‐1,2,4‐triazolo[1,5‐c][1,3]oxazepin‐6‐ones 8d‐h via the thermal reaction of the expected azinoimine lactones 6 .