光学纯反式-(+)-水合蒎醇的新方法合成

以3,5-二羟基-4-甲基苯甲酸甲酯为原料,通过7步反应,高产率地合成了反式-(+)-水合蒎醇[(+)-1],其结构通过IR,MS和NMR等技术进行了确认,该化合物的光学纯度e.e.高达99%.     

A Simple Method for Producing Micrometer-Sized Monodisperse Polystyrene Particles in Aqueous Media

A method was developed for producing micrometer-sized, highly monodisperse polystyrene particles in single stage polymerization in aqueous media. The method employs an amphoteric surfactant, dimethyldodecylbetaine, that is added to the reaction system of styrene/K(2)S(2)O(8)/water in early stage of reaction. Polymerizations were carried out over a range of initiator concentrations (4-8 mmol/dm(3) H(2)O). The polymerization procedure could produce particles with an average diameter of 3.4 μm with a coefficient of variation of particle size distribution of 4.0%. Copyright 2000 Academic Press.     

Simple Approach to the Highly Stereoselective Synthesis of trans-1,2-Cyclopropane Derivatives

In the presence of KF·2H2O, furoylmethyltriphenylarsonium bromide （1a） or thienoylmethyltriphenylarsonium bromide （1b） reacted with 2-[（un）substituted benzylidene]malononitrile （2） in chloroform at room temperature to give trans-3,3-dicyano-1-furoyl-2-[（un）substituted phenyl]cyclopropane （3a） or trans-3,3-dicyano-1-thienoyl-2- [（un）substituted phenyl]cyclopropane （3b） respectively in good yield with high stereoselectivity. The structures of product 3 were confirmed by IR, MS, 1^H NMR, 1^H-1^H COSY and microanalysis. The relative configuration of product 3 was determined by 1^H-1^H NOESY technique. The mechanism for the formation of product 3 was also proposed.     

Enantioselective total synthesis of cis-(+)- and trans-(+)-disparlure

An expedient enantioselective synthetic approach for the gypsy moth sex-attractant pheromone cis-(+)-1 and trans-(+)-disparlure 2 is described employing the optimized combination of organocatalytic MacMillan’s self aldol reaction, Wittig olefination, regioselective ring opening of an epoxide and Mitsunobu esterification reactions as key steps.     

A Simple and Efficient Device and Method for Measuring the Kinetics of Gas‐Producing Reactions

We present a new device for quantifying gases or gas mixtures based on the simple principle of bubble counting. With this device, we can follow reaction kinetics down to volume step sizes of 8–12 μL. This enables the accurate determination of both time and size of these gas quanta, giving a very detailed kinetic analysis. We demonstrate this method and device using ammonia borane hydrolysis as a model reaction, obtaining Arrhenius plots with over 300 data points from a single experiment. Our device not only saves time and avoids frustration, but also offers more insight into reaction kinetics and mechanistic studies. Moreover, its simplicity and low cost open opportunities for many lab applications.     

绿色简易法制备纯二氧化氮气体

设计了一种在密闭容器中制备纯二氧化氮气体的绿色简易方法。该方法实现了气体制备、收集、尾气处理的一体化,不仅可用于课堂演示实验,也为深入研究二氧化氮溶于水的定量实验奠定物质基础。另外,此方法也可用于无氧环境下其他物质的制备。     

trans-1,2-Dicyano-cyclopropane and other cyano-cyclopropane derivatives

In this work we present the experimental vibrational absorption (VA), vibrational circular dichroism (VCD) and Raman spectra for (+)-trans-1(S),2(S)-dicyanocyclopropane and its dideuterio derivative, trans-1(S),2(S)-dicyano-1(S),2(S)-dideuteriocyclopropane, along with VA, VCD, Raman and Raman optical activity (ROA) spectral simulations. Here we investigate the applicability of various local and non-local exchange-correlation (XC) functionals, hybrids and meta-hybrids to reproduce the vibrational spectra of this strained ring system, which also bears two cyano groups. At the highest level of theory, B3PW91/ aug-cc-pVTZ, we also investigated the trans-, cis- and gem-dicyanocyclopropane (trans-, cis-, and gem-DCCP), cyanocyclopropane (CCP) and the parent molecule cyclopropane (CP). In doing so we have investigated the electronic effects (coupling) between the cyano groups and the cyclopropane ring. In addition to providing an interpretation of the experimentally observed vibrational spectra for these molecules, this work also provides benchmark calculations for other methods, especially semi-empirical based wave function and density functional theory (DFT) based methods, such as SCC-DFTB and PM6. For the semi-empirical DFT based methods to be used for 3-membered ring systems, one ought to document their reliability for systems which were not used in the parameterization. The small 3- and 4-membered ring systems are good test systems because they contain non-standard bonding, which may be difficult to determine accurately with the approximations used in the SCC-DFTB and other semi-empirical methods. Like molecular mechanics force fields, semi-empirical methods, based on DFT and wave function quantum mechanics (WFQM), must be benchmarked against high level ab initio and DFT calculations and experimental data. In addition to bonding, the changes in the electric dipole moment, magnetic dipole moment, electric dipole-electric dipole polarizability, electric dipole-magnetic dipole polarizability and electric dipole-electric quadrupole polarizability with respect to nuclear displacement and nuclear velocity can be determined by the VA, VCD, Raman and ROA intensities. Hence it is important that the semi-empirical based DFT and wave function methods not only be parameterized to determine energies, gradients and Hessians, but also the electric and magnetic moments and their derivatives that determine the electronic and magnetic properties of these molecules and their interactions with matter and radiation. This will allow biochemists, biophysicists, molecular biologists, and physical biologists to use experimental and theoretical VA, VCD, Raman and ROA spectroscopies to probe biophysical and biochemical function and processes at the molecular level. Festschrift in Honor of Philip J. Stephens’ 65th Birthday.     

Anisotropy of polarizability of trans-1,2-dibromocyclohexanes

Conclusions On the basis of the dipole moments and Kerr constants of three trans-1,2-dibromocyclohexanes it was established that the diaxial conformers are nonpolar.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 927–928, April, 1973.     

A Simple Preparation Method for Phytochromobilin

Phytochromobilin (PΦB), the chromophore of plant phytochromes, is difficult to isolate because phytochromes occur at very low concentrations in plants. It is, therefore, frequently replaced in plant phytochrome studies by phycocyanobilin, which is abundant in cyanobacteria. PΦB is also an attractive chromophore for far‐red emitting chromoproteins. In this work, we design and optimize a simple method to efficiently isolate useful quantities of PΦB: The chromophore is generated in Escherichia coli and transiently bound to a tailored chromophore‐binding domain of ApcE2, the apo‐protein of a core‐membrane linker, from which it can subsequently be released. The ease and effectiveness of this method hinges not only on the enhanced biosynthesis of PΦB in the presence of the ApcE2 construct from Synechococcus sp. PCC7335, but also on the noncovalent binding of the pigment to its apo‐protein. The isolated PΦB was successfully incorporated into phytochrome‐related assemblies, and furthermore, the noncovalently bound PΦB could be transferred directly from the ApcE2 construct to the apo‐proteins of phytochromes, cyanobacteriochromes and phycobiliproteins, without loss of relevant biological activity.     

合成1,2-环十二二酮的新方法

以十二烷二酸（１）为原料,与甲醇酯化生成十二烷二酸二甲酯（２）,收率为８６５％。化合物２经偶联 缩合得１,２ 二三甲基硅氧基环十二烯（３）,收率为６３１％。利用溴氧化化合物３得到１,２ 环十二二酮（４）淡黄色晶体,收率７９％,全过程收率达４３.１％,是合成１,２ 二酮的新方法。目标化合物结构经红外光谱、核磁共振氢谱和碳谱表征确认。     

A Simple Alkylative 1,2-Carbonyl Transposition of Cyclohexenones

Acid catalysed dehydration of the diols 5 , derived from the cyclohexenone 3 affords mixtures of 8 and 11 . The product ratio 8/11 , although strongly dependent on both the reaction conditions and the substituent R, is independent of the diol configuration; this indicates a cationic intermediate 6 . Conditions were found, which allow the sequence A → B → C → D (Scheme 2) to be applied to the syntheses of the enones 8, 21 and 25 in fair to good yields from the corresponding cyclohexenones 3, 18 and 22 .     

Molecular structures and compositions of trans-1,2-dichlorocyclohexane and trans-1,2-difluorocyclohexane in the gas phase: an electron-diffraction investigation

The structures and compositions of gaseous trans-1,2-dichloro- (DCCH) and trans-1,2-difluorocyclohexane (DFCH), each of which may exist with the halogen atoms in a diaxial (aa) or diequatorial (ee) conformation, have been investigated by electron diffraction. The analysis was aided by rotational constants from microwave spectroscopy for the ee form of DFCH and by ab initio and density functional theory molecular orbital calculations for all species. The skeletons of the molecules have similar parameter values, but for the Cl-C-C-Cl and F-C-C-F fragments there are significant differences between the corresponding C-C-X bond angles and the X-C-C-X torsion angles in the two systems. There are also significant differences between the values of these parameters in the aa and ee forms of the same system. The composition of DCCH at 100 degrees C was measured to be 60(4)% aa, and that of DFCH at 70 degrees C was 42(7)% aa; the uncertainties are estimated 2sigma. From the preferred B3LYP/aug-cc-pVTZ calculations, the predicted theoretical composition is 51.2% aa for DCCH and 40.8% aa for DFCH. (Calculations at the levels B3LYP/6-31G(d) and MP2/6-31G(d) give similar results for DCCH, but both predict more aa than ee for DFCH.) Values (r(g)/A and angle(alpha)/degree) for some of the more important parameters of the aa/ee forms of DCCH are = 1.525(4)/1.525(6), C-Cl = 1.806(2)/1.787(2), angleC2-C1-Cl = 107.3(3)/111.5(3), angleC1-C2-C3 = 113.9(5)/111.6(5), angleC2-C3-C4 = 111.3(12)/109.9(12), and Cl-C2-C3-Cl = 165.3(9)/-59.4(9); and for DFCH C-C = 1.525(6)/1.520(9), C-F = 1.398(2)/1.390(2), angleC2-C1-F = 106.5(6)/109.2(6), angleC1-C2-C3 = 111.4(9)/110.9(9), angleC2-C3-C4 = 113.1(10)/113.1(10), and F-C2-C3-F = 171.1(37)/-67.2(37). The structures and compositions are discussed.     

强剌激性姜样味化合物Yakuchinone-A的简便合成方法

１,７二芳基庚烷类化合物（Ａｒ１Ｃ７Ａｒ２）是从山姜属、姜黄属等药用植物中分离得到结构新颖的一大类天然产物［１,２］．药理研究表明,该类天然产物不仅具有调味作用,而且还具有健胃,抗肝毒,消炎,抗溃疡,抗氧化,杀虫等多种生物活性．Ｙａｋｕｃｈｉｎ...     

环氧环戊烷的无溶剂合成工艺

以聚苯乙烯-二乙烯苯接枝磷钨酸季铵盐为三相相转移催化剂,以H2O2为氧化剂,KCl为助催化剂,研究了环戊烯(CPE)合成环氧环戊烷(CPEO)的无溶剂工艺。 讨论了催化剂和助催化剂用量、反应温度、反应时间、环戊烯与H2O2摩尔比对反应的影响。 确定了无溶剂环氧环戊烷合成反应的条件为(以0.056 mol H2O2计)：催化剂1.0 g、助催化剂0.025 g、反应温度40 ℃、反应时间5 h、n(CPE)∶n(H2O2)=2.1∶1.0。 CPEO的平均收率约为96%。 催化剂回收重复使用6次活性无明显降低。