黑沙蒿微量元素及精油的化学成分研究

本文报道了黑沙蒿微量元素及其精油化学成分的色／质谱分析结果。共鉴定出８种微量元素和８３种化学成分。     

原子吸收法对藏草药水母雪兔子和多刺绿绒蒿中12种元素的初步形态分析

用原子吸收光谱法,对产于青藏高原的藏草药水母雪兔子和多刺绿绒蒿,测定了全药材、水提液、醇提液中12种元素(Cr、Cu、Fe、Mn、Ni、Se、Zn、K、Ca、Mg、Cd、Pb)的含量,以及水提液中各元素可溶态、水溶态的含量,同时采取正辛醇-水分配体系模拟藏药水提液中各微量元素在人体胃肠中的分配情况,对藏药中微量元素的初级形态进行了分析,初步探讨了酸度变化(人体胃肠酸度)对微量元素的影响,结合藏药药效讨论其相关性,为进一步研究微量元素与藏药药性、药效的关系提供科学依据.     

奇蒿内酯晶体结构及绝对构型的测定

奇蒿内酯是从中草药刘寄奴提取的新化合物.用X射线单晶衍射方法确定了其三维结构,此单晶属单斜晶系,空间群:P21,晶胞参数:a=12.184(7),b=7.480(14),c=10.424(9)A,β=-104.44(6);Z=2.用直接法RANTAN)得分子初结构模型,采用块对角矩阵最小二乘法对此初结构进行修正,最后一致性因子R=0.085.并利用氧原子反常散射确定了分子的绝对构型。     

沙蒿胶及其羧甲基化改性产物的性能评价

为了把固沙植物沙蒿的种籽所提取的沙蒿胶开发作为水基压裂液增稠剂,评价了该植物胶及其改性产物的基本性能。结果表明,通过羧甲基化改性可使沙蒿胶的水不溶物含量由原来的55%降至4%,其表观粘度可提高两倍以上,且改性沙蒿胶的耐温性能和抗剪切性能也较好。但改性产物仍存在不易交联等缺陷,仍需对沙蒿胶的结构与性能作进一步的研究。     

蒿甲醚在模拟体内酸碱环境中的代谢动力学研究

 利用高效液相法对蒿甲醚进行了模拟体内酸碱环境的代谢动力学研究 ,测定了蒿甲醚及其代谢产物双氢青蒿素、蒿甲醚呋喃酯的代谢曲线。结果表明 ,蒿甲醚在模拟体内肠道和血液的弱碱性环境条件下半衰期为2 87 2min(计算值 ) ;在模拟体内胃液的酸性环境条件下半衰期为 74 6min ;在两种条件下的主要代谢产物均为双氢青蒿素和蒿甲醚呋喃酯。该方法克服了以往文献所报道方法的一些缺点 ,不仅简化了样品制备方法 ,也提高了检测结果的准确性。     

白蒿挥发油成分的测定及其抗氧化活性分析

采用乙醇浸提法提取生长期和花果期白蒿的挥发油,通过正交实验确定最佳提取条件为:提取3次、浸提90 min、对于生长期和花果期白蒿液料比分别为10 mL:1 g和8 mL:1 g.通过红外光谱和液相色谱-质谱联用分析了产物的主要成分,生长期白蒿挥发油的主要成分为桉树脑、樟脑、右旋龙脑、石竹烯、Cadina-1,4-diene、白菖烯、棕榈酸乙酯等;花果期白蒿挥发油的主要成分为樟脑、石竹烯、龙脑、甲酸橙花酯等.通过1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除实验对产物的自由基清除活性进行了测定,生长期和花果期白蒿挥发油对0.05 mmol/L DPPH溶液的IC50值分别为0.40和1.66 mg/mL.研究结果表明,乙醇浸提的生长期和花果期白蒿的挥发油具有较好的抗氧化活性.     

牛尾蒿中—新倍半萜结构的确定

牛尾蒿中—新倍半萜结构的确定李瑜，杨立，师彦平（兰州大学应用有机化学国家重点实验室，兰州，７３００００）关键词牛尾蒿，倍半萜，牛尾蒿酮牛尾蒿（ＡｒｔｅｍｉｓｉａＳｕｂｄｉｇｉｔａｔａ）是菊科蒿属的一种多年生草本植物，广布于华北、东北、西北和西南等地区...     

马先蒿属植物苯丙素甙成分研究(Ⅱ)

马先蒿属(Pedicularis)植物广泛分布于西北和西南地区^[1].民间多用其根或茎入药,滋阴补肾^[2].本文报道从毛颏马先蒿(P.lasiophrys)中得到的马先蒿甙E(1)和从长花马先蒿(P.longifora)中分得的马先蒿甙Ⅰ(2).     

洞庭湖区藜蒿挥发油化学成分的分析

采用水蒸气蒸馏法提取洞庭湖区野生藜蒿和人工种植藜蒿的挥发油,用气相色谱-质     

超高效液相色谱-质谱联用技术同时检测大鼠血浆中蒿甲醚及其主要代谢产物双氢青蒿素

为了研究蒿甲醚在大鼠体内的药代动力学行为,应用液液萃取-超高效液相色谱-单四极杆-静电场轨道阱串联质谱技术,建立了高灵敏度的大鼠血浆中蒿甲醚及其主要代谢产物双氢青蒿素的分析方法.以青蒿素为内标(Internal standard,I.S.),在正离子Targeted-MS2检测模式下对蒿甲醚和双氢青蒿素进行定性和定量分析.检测离子对分别为m/z 316.2115/163.1117(蒿甲醚)、m/z 302.1958/163.1117(双氢青蒿素)和m/z300.1803/209.1536(I.S.);蒿甲醚和双氢青蒿素在2～200 μg/L范围内线性关系良好(R2＞0.9990);检出限为0.8 μg/L;定量限为2.0μg/L;加标回收率分别为93.7％～103.7％和97.4％～ 104.7％;相对标准偏差均小于9％.本方法快速灵敏,重现性好,可用于蒿甲醚体内药代动力学研究.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.