Synthesis and NMR Characterization of (Z,Z,Z,Z,E,E,ω)-Heptaprenol

We describe a practical, multigram synthesis of (2Z,6Z,10Z,14Z,18E,22E)-3,7,11,15,19,23,27-heptamethyl-2,6,10,14,18,22,26-octacosaheptaen-1-ol [(Z(4),E(2),ω)-heptaprenol, 4] using the nerol-derived sulfone 8 as the key intermediate. Sulfone 8 is prepared by the literature route and is converted in five additional steps (18% yield from 8) to (Z(4),E(2),ω)-heptaprenol 4. The use of Eu(hfc)(3) as an NMR shift reagent not only enabled confirmation of the structure and stereochemistry of 4, but further enabled the structural assignment to a major side product from a failed synthetic connection. The availability by this synthesis of (Z(4),E(2),ω)-heptaprenol 4 in gram quantities will enable preparative access to key reagents for the study of the biosynthesis of the bacterial cell envelope.     

(9Z,12Z,15Z)-十八碳三烯醛的GC-MS分析

（9Z，12Z，15Z）－十八碳三烯醛是美国白蛾信息素的主要成效成分之一，在其合成的过程中，采用气相色谱监测分离提纯效果；提纯的样品成分在化学方法、IR、^1H NMR波谱分析基础上用气相色谱－质谱鉴定为该化合物，并用气相色谱的面积归一化法测得其含量大于99％；该法简单、准确可靠、无需标样。     

Vibrational analysis of the S—trans conformation of (E,E), (Z,E) and (Z,Z)-2,4-hexadienes in the gaseous and solid states

The infrared (IR) spectra of liquid, gaseous and solid states as well as the liquid and solid phases Raman ones of the pure (Z,Z)-2, 4-hexadiene are recorded for the first time between 3100–50 cm⁻¹. Furthermore, the IR spectra of the gaseous and solid states and the solid Raman ones have been obtained (3100-50 cm⁻¹) for the (E,E) and (Z,E) isomers. A comparison between the present and our previous results for the liquid phase have enabled us to complete and confirm our previous assignment and to conclude that the planar s-trans conformation is prevailing in the three physical states under conditions used in this work.     

Practical Preparation of Z‐α‐(N‐Acetylamino)‐ and Z‐α‐(N‐Benzoylamino)‐α,β‐unsaturated Acids

An efficient two‐step synthetic procedure for the preparation of numerous variations of N‐protected α,β‐unsaturated α‐amino acids and their corresponding esters from N‐protected glycine and either aliphatic or aromatic aldehydes was developed. The reaction involved cyclization of the N‐protected glycine into oxazolone, condensation with the aldehyde, and ring opening with a base.     

Structure and stability of AuXe n Z (n = 1–3, Z = −1, 0, +1) clusters

We have explored the structures and stabilities of AuXe _n ^Z (n = 1–3, Z = ?1, 0, +1) cluster series at CCSD(T) theoretical level. The electron affinities and ionization potentials are correlated to the HOMO–LUMO gaps. The role of the interaction was investigated using the natural bond orbital analysis.     

(Z,Z)-正-十二碳二烯-3,6-醇-1的合成

白蚁对建筑物危害很大,寻找防治白蚁的新手段是十分必要,早就发现白蚁的追迹行为是由一种称之为追迹信息素(trail-following pheromone)的化学物质所控制的。1968年 Matsumurat 等分别从美洲南方散白蚁(reticulitermes virginicus)及腐木菌(lenzitestrabea)腐烂的木材中分离鉴定出白蚁追迹信息素,化学结构为(Z,Z,E)-正-十二碳三烯-3,6,8-醇-1(Ⅰ)。     

Palladium-catalyzed stereoconvergent formylation of (E/Z)-β-bromo-β-fluorostyrenes: straightforward access to (Z)-α-fluorocinnamic aldehydes and (Z)-β-fluorocinnamic alcohols

We report here the stereoconvergent formylation of (E/Z)-β-bromo-β-fluorostyrene mixtures with carbon monoxide and sodium formate catalyzed by palladium. Optimization of reaction conditions leads to the corresponding pure (Z)-α-fluorocinnamaldehydes in good yields. The reaction was extended to styrenes bearing electro-attracting or electro-donating groups. The obtained α-fluoroaldehydes were smoothly reduced to the corresponding (Z)-β-fluorocinnamic alcohol by NaBH(4). The reaction could be performed on functionalized substrates as demonstrated by the access to the glucoside of β-fluoroconiferyl alcohol, (Z)-β-fluoroconiferin, a strong inhibitor of lignin polymerization.     

二氧化钛基Z型光催化剂综述(英文)

TiO_2具有无毒、耐腐蚀、高稳定和低成本等特点,已被广泛应用于光催化领域.然而,TiO_2的禁带较宽,只能吸收仅占太阳光4%的紫外光部分,从而严重限制了TiO_2光催化材料对太阳光的有效应用.目前很多方法被用来提高TiO_2光催化效率,如金属/非金属掺杂、贵金属负载、异质结构建和与碳材料复合等,这些策略在提高光催化剂的光催化效率中,涉及到如何兼顾太阳光利用和光生空穴和电子氧化还原能力两者之间的平衡.通常,半导体禁带宽度越窄,半导体的光谱响应范围越宽、太阳光利用越多,但光生空穴和电子氧化还原能力越弱.因此,想要提高TiO_2的光催化性能,应考虑以下两个方面的平衡:即降低带隙宽度,拓展半导体的光谱响应范围;与之同时使价带电位更正,导带电位更负之间的平衡.然而,这两个点是相互矛盾的,因此很难在单组分光催化剂中同时实现这两点.然而,Z型光催化剂可以同时满足这两点要求,即:降低半导体的带隙,同时使导带更负,价带更正,因为Z光催化系统利用了两种半导体的优势,其电荷转移机制类似于自然界中绿色植物的光合作用,其中的载流子传输途径包括两步激发,类似于英文字母"Z",Z型光催化剂因此而得名.Z型光催化剂既能保留较高还原能力的光生电子和又能保留较高氧化能力的光生空穴,由于Z型光催化剂特有的优点,在光催化领域的应用越来越广泛.本文综述了TiO_2基Z型光催化剂的最新研究进展,其中包括:Z型光催化机理、应用范围和光催化活性改进方法.Z型光催化剂分为传统液相Z型光催化体系,全固态Z型光催化体系,以及最近几年发展起来的直接Z型光催化体系.它们的主要应用包括:光催化分解水产氢、二氧化碳还原制备太阳燃料、有机污染物光催化降解.论文进一步讨论了提高TiO_2基Z型光催化剂性能的方法,包括pH值调控、电子导体选择、助催化剂使用、掺杂改性、组织形貌控制、两种半导体质量比优化等.最后,提出了TiO_2基Z型光催化剂今后面临的挑战和发展前景展望.     

(Z)-嘧菌酯的合成

以(E)-嘧菌酯为起始原料,经氧化和Wittig反应合成了(Z)-嘧菌酯,总收率62.3%,其结构经1H NMR和MS确证。     

(3Z, 6Z)-9S, 10R-环氧-二十一碳双烯:美洲白蛾性信息素的合成

本文报道合成美洲白蛾性信息素(3Z-6Z)-9S, 10R-环氧-二十一碳双烯(1)的路线。从双乙烯甲醇出发, 经过十步合成到1, 总得率为16.85。     

(E)-Selective hydrolysis of (E,Z)-α,β-unsaturated nitriles by the recombinant nitrilase AtNIT1 from Arabidopsis thaliana

From stereoisomeric α,β-unsaturated nitriles (E,Z)-1, the recombinant nitrilase AtNIT1 from Arabidopsis thaliana hydrolyses the (E)-isomers exclusively to the corresponding (E)-carboxylic acids (E)-2 with high specificity. The (E)-selectivity can also be utilised for the preparation of the isomerically pure nitriles (Z)-1. From (E,Z)-2-hydroxycinnamonitrile (E,Z)-3, the otherwise difficult obtainable (Z)-3 was prepared in 66% isolated yield. With β,γ-unsaturated (E,Z)-3-heptenenitrile (E,Z)-4, however, (E)-selectivity was not observed. AtNIT1 exhibits not only diastereoselectivity but also regioselectivity. From a mixture of the four isomers A–D of 3-(2-cyanocyclohex-3-enyl)propenenitrile 6, exclusively isomer D ((E)-cis-6) was hydrolysed to 3-(2-cyanocyclohex-3-enyl)propenoic acid (E)-cis-7, as stated by X-ray crystal structure. Only after complete conversion of D and high enzyme concentrations, isomer C ((E)-trans-6) was hydrolysed to a small extent.     

(Z)-homo-β-Santalol: Synthese und Geruch

Summary The synthesis of the title compound is described. Starting with the -alkylation ofhomo-norcamphor followed by aWittig reaction, aTebbe transformation, and aDIBAH ester-reduction as the most important reactions of a 5 step sequence, (Z)-homo--santalol was obtained, which exhibits the typical precious sandalwood odour. The moderate increase of the volume of the bulky group obviously does not alter the odour quality sandalwood of this new -santalol analogue.

     

Synthesis,halogenation and structural characterization of (Z)-1-[2-(triphenylstannyl)vinyl]-l-cyclododecanol

Synthesis and characterization of (Z)-1-[2-(triphenylstannyl)vinylj-l-cyclododecanol,c-(CH2)11C(OH)CH=CHSnPh3,are reported,together with its halogenation by I2,Br2 and IC1 to yield derivatives of the types c-(CH2)11C(OH)CH=CHSnPh3_nXn (n=1,2; X=I,Br,Cl,respectively).The molecular structures of two compounds have been determined by X-ray diffraction analysis.The tin atom exhibits a distorted tetrahedral geometry in the crystal of (Z)-1-[2-(triphenylstannyl)vinyl]-1-cyclododecanol,but a trigonal bipyramidal geometry in the monoiodo-derivative (Z)-1-[2-(diphenyliodo-stannyl)vinyl]-l-cyclododecanol and other derivatives,in which significant intramolecular coordinative interaction HO→Sn is observed.And the formation of a five-membered tin containing ring is significant for their antitumour activities.     

A Stereoselective Synthetic Route To (Z)-α-Stannyl-α, β-Unsaturated Aldehydes

Acetylenic stannanes 1 react with Cp₂Zr(H)Cl (Cp = η⁵-C₅H₅) and CO to give acylzirconocene chloride derivatives 2, which are trapped with dilute HCl to afford (Z)-α-stannyl-α, β-unsaturated aldehydes 3.     

Facile Syntheses of (±)-Curcuphenol, (±)-Curcudiol, (±)-Curcuhydroquinone,and (±)-Curcuquinone

The syntheses of (±)-curcuphenol 1, (±)-curcudiol 2, (±)-curcuhydroquinone 3, and (±)-curcuquinone 4 have been achieved. The key steps involved in the syntheses were the Reformatsky reaction and hydrogenation reaction.     

Synthese und Geruch von (Z)-Dehydro-homo-β-santalol

Summary Guided by molecular modeling studies, the synthesis of the title compound is described. The organoleptic evaluation proved the predicted real sandal like odour of (Z)-dehydro-homo--santalol.

Aus den Diplomarbeiten von C.P. (1991), I.P. und B.Ö. (1992), Universität Wien     

Stereoselective Synthesis of (Z)-β-Aryltellurocinnamic Esters

ＳｔｅｒｅｏｓｅｌｅｃｔｉｖｅＳｙｎｔｈｅｓｉｓｏｆ（Ｚ）－β－ＡｒｙｌｔｅｌｌｕｒｏｃｉｎｎａｍｉｃＥｓｔｅｒｓ￥ＣｈａｎｇＱｉｕＺＨＡＯ；ＸｉａｎＨＵＡＮＧ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＨａｎｇｚｈｏｕＵｎｉｖｅｒｓｉｔｙ，Ｈａｎ...     

Thermal reaction of [3,4]-benzo-8-substituted-3Z,5Z,7E-octatetraenes and quantum-chemical study of the (8π,6π)-electrocyclisation

The first example of thermal (8π,6π)-electrocyclisation of 1,3,5,7-octatetraene with one double bond embedded in an aromatic moiety is described. By this process, [3,4]-benzo-8-substituted octatetraene derivatives, the cis,trans-1-(o-vinylphenyl)-4-(R = Me, Ph, 2-furyl)buta-1,3-dienes were transformed to a new endo-7-(R = Me, Ph, 2-furyl) and exo-7-(R = Me)-2,3-benzobicyclo[4.2.0]octa-2,4-dienes. Mechanism of reaction was also studied by DFT quantum-chemical calculations. The M06/6-311+G(d,p)//M06/6-31+G(d,p) calculations indicate that formation of the single endo-isomer in the case of phenyl and 2-furyl substituents is determined by higher activation barriers for exo-6π-electrocyclisation than for 8π-cycloreversion.     

A Convenient and Stereospecific Synthesis of (Z)-Benzylidenephthalides

Several 3-benzylidenephthalides have been isolated from natural sources1-2. Some of them are known to possess useful biological activity1 and are also valuable intermediates3 for the synthesis of naturally occurring biologically active compound. Most of the natural 3-benzylidenephthalides exist in the (Z)-configuration. Synthe-tic methods for construction of a 3-benzylidene-phthalide skeleton have been developed4. Some of these methods for synthesizing highly oxygen-functionalized compound…