微量元素与阿尔茨海默病(7)

阿尔茨海默病(AD)是目前老年人最为关注的重要健康问题。中国55岁以上人群的AD患病率已超过2.0%,患病总人数在600万以上,中国已成为全球痴呆人数最多、速度增加最快的国家。至今人们对该病病因及其机制的了解仍然有限,亦无有效的药物可以阻止和治疗该病的发生和发展。该文在前人研究的基础上,全面总结并提出了该病病理的微量元素稳态障碍假设,详尽阐述了新学说的三个组成部分及四个方面的实践证据。     

Cp*MCpMoFe(CO)7(μ3-S), Cp*MoCpMFe(CO)7(μ3-S) (M = W,Mo) and Cp*WCp*MoFe(CO)7(μ3-S). Crystal structure of CpMoCp*WFe(CO)7(μ3-S)

CpMoFeCo(CO)₇(₃-S) reacts with Cp^*M(CO)₃Cl or CpM(CO)₃Cl (M=W, Mo) to gave the mixed-metal clusters Cp^*WCpMoFe(CO)₇(₃-S) (1), Cp^*MoCpMoFe(CO)₇(₃-S) (2), CpWCp^*MoFe(CO)₇(₃-S) (3), CpMoCp^*MoFe(CO)₇(₃-S) (4) and Cp^*WCp^*MoFe(CO)₇(₃-S) (5). The title clusters have been characterized by i.r., ¹H/¹³C-n.m.r. spectroscopy and their compositions have been confirmed by elemental analyses. The X-ray crystal structure analysis shows the two independent enantiomeric molecules of clusters (1) in one crystal structure unit.     

Schiff碱(C7H7NO)钯(Ⅱ)配合物的合成与晶体结构

合成了N—H水杨醛Sch iff碱的钯(Ⅱ)配合物.X射线单晶衍射表明,配合物晶体属于单斜晶系,Pī空间群,分子式为C48H50N8O8Pd3,晶体学参数:a=0.945 8(19)nm,b=1.059 9(2)nm,c=1.396 5(3)nm,α=74.61(3),°β=75.18(3)°,γ=68.49(3)°,V=1.236(4)nm3,Dc=1.594 Mg/m3,Mr=1 186.16,Z=1,F(000)=596,R1=0.029 9,wR2=0.073 4.晶体结构表明,钯原子为四配位,位于配合物的中心与配体的氮原子和氧原子结合形成六元环.     

Synthesis of (±)-7-hydroxylycopodine

A six step synthesis of (±)-7-hydroxylycopodine has been achieved in 5% overall yield. In the key step, a Prins cyclization of a bicyclic keto alkyne in 60% H(2)SO(4) forms a tricyclic dihydroxy amino ketone.     

Synthesis of (±)-7-hydroxylycopodine

A seven-step synthesis of (±)-7-hydroxylycopodine that proceeds in 5% overall yield has been achieved. The key step is a Prins reaction in 60% sulfuric acid that gave the key tricyclic intermediate with complete control of the ring fusion stereochemistry. A one-pot procedure orthogonally protected the primary alcohol as an acetate and the tertiary alcohol as a methylthiomethyl ether. The resulting product was converted to 7-hydroxydehydrolycopodine by heating with KO-t-Bu and benzophenone in benzene followed by acidic workup. During unsuccessful attempts to make optically pure starting material, we observed the selective Pt-catalyzed hydrogenation of the 5-phenyl group of a 4,5-diphenyloxazolidine under acidic conditions and the Pt-catalyzed isomerization of the oxazolidine to an amide under neutral conditions. In attempts to hydroxylate the starting material so that we could adapt this synthesis to the preparation of (±)-7,8-dihydroxylycopodine (sauroine) we observed the novel oxidation of a bicyclic vinylogous amide to a keto pyridine with Mn(OAc)(3) and to an amino phenol with KHMDS and oxygen.     

(μ3-S)FeCo2(CO)7(dppfe)的合成和晶体结构

通过简单取代反应,合成了一个新的混金属簇合物(μ3-S)FeCo2(CO)7(dppfe) (2) (dppfe=Ph2PC5H4FeC5H4PPh2).利用IR,1H NMR,MS 和 X-ray单晶衍射的方法对簇合物2进行了结构表征.簇合物2的晶体属于三斜晶系,空间群为Pī.晶胞参数: a=1.132 4(15) nm, b=1.3670(17) nm, c=1.5769(2) nm,α=114.646(2)°,β=100.340(2)°,γ=100.113(3)°, V=2.0953(5) nm3.     

(μ3-S)FeCo2(CO)7(dppfe)的合成和晶体结构

通过简单取代反应,合成了一个新的混金属簇合物(μ3-S)FeCo2(CO)7(dppfe)(2)(dppfe=Ph2PC5H4FeC5H4PPh2).利用IR,1HNMR,MS和X-ray单晶衍射的方法对簇合物2进行了结构表征.簇合物2的晶体属于三斜晶系,空间群为Pī.晶胞参数:a=1.1324(15)nm,b=1.3670(17)nm,c=1.5769(2)nm,α=114.646(2)°,β=100.340(2)°,γ=100.113(3)°,V=2.0953(5)nm3.     

R_(15)Fe_(78)B_7的磁晶各向异性

用磁测量和X-射线衍射方法研究了R_(15)Fe_(78)B_7(R=Pr,Nd,Sm,Gd,Y)的磁晶各向异性。发现R=Pr,Gd和Y时,无论室温或低温,c轴都是易磁化方向;R=Sm时,易磁化方向都是在与c轴垂直的基面内;而R=Nd时,易磁化方向随温度变化。在室温时,c轴是易磁化方向,但当温度低于140K时,易磁化方向相对c轴形成一个θ角度。利用Sucksmith-Thompson方法估算了R_(15)Fe_(78)B_7的磁晶各向异性常数K_1和K_2的数值和符号;测量了θ与温度的依赖关系。并通过测定Nd_(15)Fe_(78)B_7和Y_(15)Fe_(78)B_7的磁晶各向异性及其随温度的变化,进一步分析了Nd_(15)Fe_(78)B_7中Nd和Fe不同次点阵对磁晶各向异性的贡献。     

(±)-Cycloaltilisin 7和(±)-Poinsettifolin B的首次全合成

Cycloaltilisin 7是从桑科植物面包树(Artocarpus altilis)的芽中分离出的一种新异戊烯基黄烷酮,具有组织蛋白酶K抑制活性;Poinsettifolin B也是从桑科琉桑属植物Dorstenia poinsettifolia中分离出的一种新的香叶基查尔酮,Dorstenia poinsettifolia是原产于喀麦隆潮湿森林的草本植物,用于民间雅司病和伤口感染的治疗,对治疗皮肤病也有潜在功效.以廉价的羟苯乙酮和羟苯甲醛为原料,用简单温和的方法完成了这两种天然产物的首次全合成.所有新化合物的结构都经过HRMS,1H NMR和13C NMR的确认.     

Templating an organic array with Si(111)-7×7

We demonstrate that nearest neighbor molecular adsorption can be sterically hindered on the Si(111)-7×7 surface reconstruction. This breaks the energetic equivalence of corner and edge di-σ attachment geometries and allows a translationally ordered organic layer to be templated directly on the 7×7 reconstruction.     

Reactive epitaxy of beryllium on Si(1 1 1)-(7×7)

Scanning tunneling microscopy (STM) and photoelectron spectroscopy (PES) have been used to investigate the nucleation, growth, and structure of beryllium on Si(1 1 1)-(7×7). STM indicates that a chemical reaction occurs at temperatures as low as 120 K, resulting in a nano-clustered morphology, presumed to be composed of a beryllium silicide compound. Upon annealing to higher temperatures, PES data indicate that beryllium diffuses into the selvage region. High temperature annealing (∼1175 K) results in the formation of a universal ring cluster structure suggesting a Be–Si bond length less than 2.5 Å, in agreement with previous calculations regarding hypothetical Be₂Si.     

Total synthesis of (±)-7-epi-nemorosone

A concise total synthesis of (±)-7-epi-nemorosone is reported. Our synthetic approach establishes a viable route to polycyclic polyprenylated acylphloroglucinol natural products (PPAP's) bearing a C-7 endo prenyl side chain. Key steps include retro-aldol-vinyl cerium addition to a hydroxy adamantane core scaffold and palladium-mediated deoxygenation.     

First Total Synthesis of (-)-4-O-(6'-hydroxy-7'(9')-dehydro-6',7'-dihydrogeranyl)-coniferyl Alcohol

SomeLigulariaspecieshavelongbeenusedasfolkremediesduetotheirantibiotic,antiphlogisticandantitumoracti.ities'.Compound1',anovelconiferylalcoho1,wasisolatedfromLigulariaduciformis(Compsitae)alongwiththreenewstructuressuchas2,3,4(Figure1).Thegeometricalstructureof1,deterndnedbyspectroscopictechniques,correspondedto4-o-(6'-hydroxy-7'(9')-dehydro-6coniferylalcohol.ButitsabsoluteconfigurationatC-6'hasnotyetbeendetermined.Hereinwereportthetotalsynthesisof(6'S)-(-)-lfromgeraniol5throughninesteps(Sc…