叶绿素-b的结构修饰及其二氢卟吩类衍生物的合成

在含有5％的硫酸甲醇溶液中,通过去除金属镁离子和酯交换反应将叶绿素-b降解为脱镁叶绿酸-b甲酯,在二苯醚中的热裂解进一步将其转化为焦脱镁叶绿酸-b甲酯.通过乙酸中的空气氧化得到132-羟基脱镁叶绿酸-b甲酯和132-羟基焦脱镁叶绿酸-b甲酯,前者和脱镁叶绿酸-b甲酯在碱性条件下继续与空气中氧分子作用均给出相应的氧化产物.C3-乙烯基与重氮甲烷1,3偶极环加成及热裂解反应生成C3-吡唑啉基和环丙基取代的二氢卟吩衍生物;C7-甲酰基与溴化三苯基苄基鳞的Wittig反应给出C7-苯亚甲基取代的二氢卟吩衍生物.所合成新的二氢卟吩类衍生物均经UV,IR,1HNMR光谱及元素分析证明其结构.与此同时,对相应的反应提出了可能的反应机理.     

具有叶绿素基本碳架的C-3-异噁唑啉基二氢卟吩类衍生物的合成

以脱镁叶绿酸-a甲酯为起始原料,通过3-位乙烯基与氧化苯甲腈和4-取代氧化苯甲腈的1,3-偶极环加成反应,分别得到3-位异噁唑基取代的二氢卟吩衍生物以及其他形式的加成产物,对其脱镁叶绿酸的E-环结构修饰则转换成相应的二氢卟吩-p6衍生物;脱镁叶绿酸-a甲酯经空气氧化和重排反应形成了红紫素-18-内酰胺,再与4-取代氧化苯甲腈进行相同的环加成反应,也以理想的产率生成标题化合物.所得新的二氢卟吩衍生物的化学结构均经UV,IR,1H NMR 及元素分析得以证实,并对相应的反应提出可能的反应机理.     

具有长波吸收的(焦)脱镁叶绿酸衍生物的合成及其电子光谱

以脱镁叶绿酸-a甲酯和脱镁叶绿酸-b甲酯为起始原料,通过3-位乙烯基、外接E-环和20-meso-位的化学修饰,在脱镁叶绿酸-a甲酯周环上建立了不同的羰基结构.利用脱镁叶绿酸-a甲酯的所建羰基和脱镁叶绿酸-b甲酯的原有7-位甲酰基分别与丙二睛进行Knoevenagel缩合反应,在二氢卟吩的不同位置引进了β,β-二氰亚甲基结构,完成一系列具有长波吸收的叶绿素类二氢卟吩衍生物的合成,讨论了β,β-二氰亚甲基的引入对大环分子的化学活性和电子光谱的影响,并对相应的化学反应提出可能的反应机理.未见报道的10个叶绿素-a衍生物均经UV,IR,1H NMR及元素分析证明其结构.     

（焦）脱镁叶绿酸－a甲酯的N~(21)N~(23)轴向化学结构修饰及其对可见光吸收的影响

以脱镁叶绿酸－a甲酯和焦脱镁叶绿酸-a甲酯为起始原料，通过3－位乙烯基和 13~1-位环上基的化学反应，改变二氢中卟吩母环上N~(21)-N~(23)轴向的化学结构 ，完成了（焦）脱镁叶绿酸－a甲酯衍生物2～15的合成，并对其可见光谱的变化进 行了讨论。所合成的新叶绿酸衍生物均经UV，IR，~1H NMR及元素分析证明其结构 。     

(Z)-焦脱镁叶绿酸-a甲酯-(E)-环酮肟的化学反应及其衍生物的合成

以焦脱镁叶绿酸-α甲酯为起始原料并转化成(E/Z)-焦脱镁叶绿酸-131-酮肟,经历与NCS的亲电取代、硝酸铊或四氧化锇的氧化以及与重氮甲烷的1,3-偶极环加成等不同化学反应,生成了一系列二氢卟吩化合物.新合成的叶绿素衍生物的化学结构均经紫外-可见光谱、红外光谱、核磁共振光谱和元素分析予以确认.     

具有叶绿素-a基本骨架的20-meso-位取代二氢卟吩衍生物的合成

以脱镁叶绿酸-a甲酯(MPa)为起始原料,分别与氯化、溴化和硫酸重氮苯进行偶联反应,其主要产物为20-卤素取代或者亚硝基取代的二氢卟吩,仅以微量产率的得到期待的产物.焦脱镁叶绿酸的锌配合物与3-N,N-二甲胺基丙烯醛的Vilsmeier反应生成20-甲酰乙烯基焦脱镁叶绿酸.焦脱镁叶绿酸-d与N-溴代丁二酰亚胺(NBS)的溴代反应生成单一的20-溴代产物,再经Wittig反应恢复乙烯基而得到20-溴代焦脱镁叶绿酸-a甲酯.其它叶绿素降解产物的亲电取代反应均以较好的产率得到生成的20-meso-位取代的二氢卟吩衍生物.首次报道的具有叶绿素基本碳架的二氢卟吩衍生物的化学结构均经UV,IR,1H NMR及元素分析得以证实.     

具有叶绿素基本碳架的苯并咪唑并红紫素-18衍生物的合成

脱镁叶绿酸-a甲酯与邻苯二胺发生缩合和重排反应,分别给出(2,3-n)-苯并咪唑并红紫素-18甲酯、(2,3-o)-苯并咪唑并红紫素-18甲酯、(2,3-n)-喹喔啉并焦脱镁叶绿酸甲酯和二氢卟吩-p6三甲酯.针对苯并咪唑并红紫素-18的20-meso-位和12-位甲基进行氟代、氯代、溴代、碘代和空气氧化反应,完成了一系列具有叶绿素基本碳架的苯并咪唑并二氢卟吩类衍生物的合成.所得新的叶绿素衍生物的化学结构均经UV,IR,1H NMR,质谱及元素分析予以证实.     

3-位苯并含氮杂环取代的焦脱镁叶绿酸-α甲酯的合成

以焦脱镁叶绿酸-a甲酯(MPP-a)(1)为起始原料,在二氯甲烷中与醋酸锌共回流得锌配合物2,在四氯钯锂催化下,通过与苯基氯化汞的偶联反应生成3b-苯基焦脱镁叶绿酸-a甲酯(3).分别选用四氧化锇、高钌酸四丙基铵(TPAP)和N-甲基吗啉N-氧化物将环外烯键氧化成邻二酮(4).在酸性条件下,4与邻苯二胺的缩合形成了3-位喹喔啉取代的焦脱镁叶绿酸-a甲酯(5).用四氧化锇和高碘酸钠将l的3-位碳碳双键氧化,则生成焦脱镁叶绿酸-d甲酯(6).所得卟吩醛与环己二酮和萘胺进行一锅法反应,得到3-位苯并吖啶取代的焦脱镁叶绿酸-a甲酯(7).所合成的新卟吩化合物均经UV,IR,1H NMB及元素分析证明其结构.     

焦脱镁叶绿酸的炔化反应及其叶绿素类二氢卟吩的合成

以焦脱镁叶绿酸-a甲酯为起始原料,利用加成和氧化反应将其转化成3-甲酰基或者3-乙酰基取代和E-环保护的反应前体,通过Grignard反应在3-位上引进炔基并构建了叔醇或者仲醇结构,再经脱水和氧化反应生成端位烯炔和炔酮取代的二氢卟吩衍生物.3-甲酰基焦脱镁叶绿酸-a甲酯与癸基溴化镁的Grignard反应、E-保护和C(3)-羟基的氧化反应得到C(3)-长链烷酰基取代的焦脱镁叶绿酸-a甲酯,再经酸催化脱水则得到含有链间烯炔结构的二氢卟吩.首次报道的叶绿素类二氢卟吩衍生物均经UV,IR,1H NMR及元素分析确定其化学结构,对相应的化学反应也提出了可能的反应机理.     

3-位苯并含氮杂环取代的焦脱镁叶绿酸-a甲酯的合成

以焦脱镁叶绿酸-a甲酯(MPP-a)(1)为起始原料，在二氯甲烷中与醋酸锌共回流得锌配合物2，在四氯钯锂催化下，通过与苯基氯化汞的偶联反应生成3b-苯基焦脱镁叶绿酸-a甲酯(3)．分别选用四氧化锇、高钌酸四丙基铵(TPAP)和N-甲基吗啉N-氧化物将环外烯键氧化成邻二酮(4)．在酸性条件下，4与邻苯二胺的缩合形成了3-位喹喔啉取代的焦脱镁叶绿酸-a甲酯(5)．用四氧化锇和高碘酸钠将1的3-位碳碳双键氧化，则生成焦脱镁叶绿酸-d甲酯(6)．所得卟吩醛与环己二酮和萘胺进行一锅法反应，得到3-位苯并吖啶取代的焦脱镁叶绿酸-a甲酯(7)．所合成的新卟吩化合物均经UV，IR，^1H NMR及元素分析证明其结构．     

Electron attachment to MoF6, ReF6, and WF6; reaction of MoF6(-) with ReF6 and reaction of Ar+ with MoF6

Rate constants were measured for electron attachment to MoF(6), ReF(6), and WF(6) in 133 Pa of helium gas using a flowing-afterglow Langmuir-probe apparatus. The experiment is a thorny one because the molecules tend to form oxide impurities on feedline surfaces and because of thermal decomposition of MoF(6) on surfaces as the gas temperature is increased. The electron attachment rate constant for MoF(6) is (2.3+/-0.8)x10(-9) cm(3) s(-1) at 297 K; only MoF(6) (-) is formed in the temperature range of 297-385 K. The rate constant increases with temperature up to the point where decomposition becomes apparent. Electron attachment to ReF(6) occurs with a rate constant of (2.4+/-0.8)x10(-9) cm(3) s(-1) at 297 K; only ReF(6) (-) is produced. MoF(6) (-) reacts with ReF(6) to form ReF(6) (-) on essentially every collision, showing definitively that the electron affinity of ReF(6) is greater than that of MoF(6). A rate constant of (5.0+/-1.3)x10(-10) cm(3) s(-1) was measured for this ion-molecule reaction at 304 K. The reverse reaction is not observed. The reaction of Ar(+) with MoF(6) was found to produce MoF(5) (+)+F, with a rate constant of (1.8+/-0.5)x10(-9) cm(3) s(-1). WF(6) attaches electrons so slowly at room temperature that the attachment rate was below detection level (< or =10(-12) cm(3) s(-1)). By 552 K, the attachment rate constant reaches a value of (2+/-1)x10(-10) cm(3) s(-1).     

C60NH5/6, 6/6异构体的理论研究

用半经验的AM1, PM3及ab initio方法对C60NH两种异构体的结构及光谱进行了理论计算。结果表明, 具有开环结构的C60NH的5/6异构体稳定性要高于具有闭环结构的6/6异构体。计算了两种异构体开环与闭环过程的反应坐标, 发现6/6开环异构体是势能面上的一局部最小点, 而5/6闭环异构体不存在6/6异构体的H可以在两种镜面异构体之间快速翻转, 使其核磁共振谱呈现C2v对称性。通过振动分析确认了所优化的构型确实为势能面的能量最低点, 并得到了C60NH各异构体的红外光谱。     

Arachno, nido, and closo aromatic isomers of the Li6B6H6 molecule

We analyzed chemical bonding in low-lying isomers of the recently computationally predicted B(6)H(6)Li(6) molecule. According to our calculations the benzene-like B(6)H(6)Li(6) (D(2h), (1)A(1g)) arachno structure with the planar aromatic B(6)H(6)(6-) anion is the most stable one. A nido isomer with two aromatic B(6)H(6)(4-) (pentagonal pyramid) and Li(3)(+) (triangular) moieties, which can be considered as derived from the global minimum structure through a two-electron intramolecular transfer from B(6)H(6)(6-) to three Li(+) cations, was found to be 10.7 kcal/mol higher in energy. A closo isomer with three aromatic moieties (octahedral B(6)H(6)(2-) and two Li(3)(+)) was found to be 31.3 kcal/mol higher in energy than the global minimum. Another isomer with three aromatic moieties (two B(3)H(3)(2-) and Li(3)(+)) was found to be substantially higher in energy (74.4 kcal/mol). Thus, the intramolecular electron transfers from the highly charged B(6)H(6)(6-) anion to cations are not favorable for the B(6)H(6)Li(6) molecule, even when a formation of three-dimensional aromatic B(6)H(6)(2-) anion and two sigma-aromatic Li(3)(+) cations occurs in the closo isomer.     

In search of benzene-like Sn6(6-): synthesis of Na4CaSn6 with interconnected cyclohexane-like Sn6(6-)

The title compound was synthesized in an attempt to produce stacked benzene-like Sn6(6-) rings separated by alkaline-earth cations in analogy with the recently reported stacks of aromatic cyclopentadienyl-like Sn5(6-) in Na8BaSn6 (in addition to isolated Sn4- anions). The resulting compound, synthesized from a stoichiometric mixture of the elements at high temperature, has the "correct" stoichiometry with six tin atoms and six positive charges. However, the rings of Sn6(6-) are puckered into chair-type cyclohexanes that are interconnected into isolated cylindrical tubes stuffed with Ca2+ between the rings. Such tubes, if fused to each other, form the hexagonal diamond structure. The new compound is electronically balanced according to magnetic and four-probe resistivity measurements. Reported are also the synthesis and properties of Na10EuSn12 and Na10YbSn12 which are isostructural with the known Na10CaSn12.     

Facile Syntheses of (6S)-6-Fluoroshikimic Acid and (6R)-6-Hydroxyshikimic Acid

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Ordnungszustände im system polyamid-6 und polyamid-6, 6

Blends of PA-6 and PA-6,6 were studied by DSC for different conditions of crystallization. All samples were characterized by x-ray diffraction. From dilute solution the components crystallize in separate modifications. In the melt both components are compatible. PA-6- and PA-6,6-segments are linked together. During rapid quenching of the melt in the samples of about equal composition of PA-6 and PA-6,6 a modification is formed possibly built by a three-dimensional network of hydrogen bonds between PA-6- and PA-6,6-segments. If the samples of the same composition are annealed at 25 K below the melting temperatures of PA-6 and PA-6,6 for 3 hours in each case a modification appears as in quenched samples in addition to only partially ordered crystallites of PA-6 and PA-6,6. Despite optimal annealing there is no complete separation of the components.     

Reaction of 6-quinoline aldehyde with rhodanines and 2, 6-dimethylquinoline

The crotonaldehyde type of condensation of 6-quinolylaldehyde and its methiodide with 3-methyl-3-ethyl-, and 3-allylrhodanines is investigated. 5-(Quinolidene-6-)-3-alkylrhodanines and their monomethiodides are synthesized. 2-[2-(Quinolyl-6) ethenyl]-6-methylquinoline is prepared by condensing 6-quinolylaldehyde with 2,6-dimethylquinoline.     

Synthesis of the 6-6-6 tricyclic skeleton of the anti-influenza A diterpene wickerol A

A five-step synthesis of the 6-6-6 tricyclic skeleton of the diterpene wickerol A is described. The synthesis features a diastereoselective d-proline-mediated Robinson annulation and N-heterocyclic carbene-catalyzed Stetter reaction as key transformations to give the tricyclic carbon skeleton of this promising anti-influenza A natural product.     

Synthesis of [6-6-6] ABE tricyclic ring analogues of methyllycaconitine

A new synthesis of the bridged [6-6-6] ABE tricyclic ring analogues of methyllycaconitine with the C-1 oxygenated substituents has been developed using an efficient aza-annulation of β-enamino ketone followed by a facile decarboxylation to form BE rings. Subsequent elaboration to form the A ring was achieved by a transannular acyl radical cyclization with concomitant equipment of the key C-1 oxygen functionality.