几何的和手性的昆虫信息素及其合成的进展

昆虫信息素是高生理活性的化学信使,它们是为一些种类的昆虫成员所分泌,并对同种昆虫的其它成员引起强烈的行为反应。昆虫信息素的研究已引起了人们极大的重视,这不仅是因为科学上的兴趣,也是因为害虫控制的应用前景。以前作为化学信使的昆虫信息素总被认为是单一的化合物,并且这些信息素大都是     

昆虫信息素结构鉴定方法进展

昆虫信息素是昆虫在进行集合、追踪和配偶等行为活动时所分泌而用以传递信息的化学物质。近十多年来,这方面的研究工作非常活跃,发展很快。其中又以鳞翅目性信息素研究得最多,其特点为:(1)活性极高,几百个     

昆虫性信息素的合成

在昆虫界,同种昆虫的异性之间为着配偶的需要,分泌出一些化学物质来传递信息。人们称这种化学物质为昆虫性信息素,也称为昆虫性诱剂。由于昆虫个体中的性信息素存在量极微,所以对其化学研究有一定的困难。Bute-nandt等人经过 20年(1939—1959)的努力,首次从50万头家蚕(Bombyx mori)中分离到12毫克纯粹性信息素的衍生物,并最后鉴定出蚕蛾性信息素的化学结构。之后,由于近代超微量分离鉴定技术的发展,促进了人们对昆虫性信息素的研究。现在人们已从虫体中分离、鉴定出     

铅的生物富集效应

铅以微量元素的含量水平，广泛分布于动、植物的人体中。对比大量的动植物种群及各种年龄组的人群，似乎铅在一定的分子组态，特别是生物有机铅，不一定都是有害物质。相反可起一定的新陈代谢调节作用。或者可称为新陈代谢调节剂。特别是在动物、植物、人体中铅为微量、超微量状态时，铅更显现调节作用。     

欧洲玉米螟性信息素合成方法的研究

我们对欧洲玉米螟性信息素的主要成份的合成方法进行了选择性的研究,欧洲玉米螟性信息素主要由顺-11-十四烯-1-醇乙酸酯(Ⅰ)和反式-11-十四烯-1-醇乙酸酯(Ⅱ)组成,不同地区的欧洲玉米螟性信息素所含的顺、反异构体比例有所不同,在欧洲及加拿大,这种害虫性信息素顺、反异构体比例是97:3。     

手性甲基脂肪烃类昆虫信息素的合成研究进展

手性甲基脂肪烃类昆虫信息素包括单手性甲基、双手性甲基和多手性甲基脂肪烃类昆虫信息素,在棘翅夜蛾、南部云杉天牛、桃潜叶蛾等多种农林害虫的绿色防控领域具有极具发展的前景.按手性甲基的构建方法,分类阐述了单手性甲基昆虫信息素的合成方法;根据手性甲基片段的连接策略对双手性甲基与多手性甲基脂肪烃类昆虫信息素的合成方法进行了详细介绍;并对各种合成方法的优势与不足进行简单讨论,以及对手性甲基脂肪烃类昆虫信息素的合成研究进行了展望.     

这里不应用溴水鉴别——对2002年全国高考理综合第28题答案的质疑

2002年全国高考理综合卷第28题是生物和化学科的综合题(原题略),全题以昆虫分泌的信息素结构简式为载体,其中工小题着重考查了结构中碳碳双键和醛基的实验室鉴别方法、实验现象和化学方程式以及反应类型,是化学实验中最基础的考查内容。     

德国小蠊性信息素类似物的设计与合成

德国小蠊是世界上最难治理的卫生害虫之一.昆虫性信息素可作为一种安全有效的引诱剂用于害虫的综合治理.德国小蠊性信息素(blattellaquinone)因其结构不稳定而妨碍了它的实际应用.为了发现结构新颖且稳定的性信息素类似物,对blattellaquinone的结构中苯醌(A)、酯基(B)和脂肪链(C)部分进行了改造,设计并合成了一系列类似物,结构均通过1H NMR,IR和HRMS分析确证.     

葡萄糖敏感型水凝胶最新研究进展

糖尿病是由于胰岛素分泌不足引起的一种新陈代谢疾病,对糖尿病的有效控制在于不间断的测定血糖浓度并适时的释放胰岛素.因此,能够对环境葡萄糖浓度变化做出应答的功能型高分子材料葡萄糖敏感水凝胶,在生物化学和生物医学领域引起了极大的关注.本文综述了近几年国内外葡萄糖敏感型水凝胶的研究现状,重点介绍了应用于胰岛素释放体系和生物传感器领域的载有葡萄糖氧化酶、伴刀豆球蛋白和苯硼酸基团等葡萄糖敏感型水凝胶的作用机理和最新研究进展,展望了今后的研究方向.     

高纯度的棉铃虫性信息素主要组份的合成

棉铃虫(Heliothis amigora)是世界性棉花害虫,在我国产棉区的危害也甚为严重.棉铃虫性信息素主要组份为顺-9-十六碳烯醛-1(1)和顺-11-十六碳烯醛-1(2)等烯醛类化合物.1和2的合成报道是以 Wittig 反应为主或炔锂和卤代烷缩合,这种合成路线所得的1和2.其顺式双键的纯度均仅95～98％,总产率约35％.因为昆虫对信息素的几何异构体组成非常敏感.所以几何异构体的纯度在合成昆虫信息素中特别重要.为此我们选择了用顺-二(烯基)铜锂的烷基化反应合成1和2(图式1A).得到了>99.5％顺式构型的产物.用此法不仅合成步骤短,而且总产率高达80％.此外用本法还可通过变换图式1中的 m 或 n 数得到一系列双键位置不同的长链脂肪醛、醇及其乙酸酯的昆虫性信息素化合物.溴化物3和锂反应生成的锂试剂与碘化亚铜,乙炔及碘代烷通过一步反应即生成顺式烯化合物4,产率90％.然后除去4的保护基团和再经 PCO 氧化,得1和2,总产率分别为79.5％     

Unusual reactivity patterns of 1,3,6,8-tetraazatricyclo-[4.4.1.1(3,8)]-dodecane (TATD) towards some reducing agents: synthesis of TMEDA

N,N,N,N-tetramethylethylenediamine (TMEDA) can be synthesized by simple reduction of 1,3,6,8-tetraazatricyclo-[4.4.1.1.(3,8)]dodecane (TATD), an aminal cage type amine, with formic acid. The aminal can be converted to TMEDA in high yield very easily and in a very short time. We comment on the scope and limitations of the reduction of this aminal and propose a possible reaction mechanism.     

One‐Pot Three‐Component Synthesis of Vicinal Diamines via In Situ Aminal Formation and Carboamination

A synthesis of vicinal diamines via in situ aminal formation and carboamination of allyl amines is reported. Employing highly electron‐poor trifluoromethyl aldimines in their stable hemiaminal form was key to enable both a fast and complete aminal formation as well as the palladium‐catalyzed carboamination step. The conditions developed allow the introduction of a wide variety of alkynyl, vinyl, aryl, and hetereoaryl groups with complete regioselectivity and high diastereoselectivity. The reaction exhibits a high functional‐group tolerance. Importantly, either nitrogen atom of the imidazolidine products can be selectively deprotected, while removal of the aminal tether can be achieved in a single step under mild conditions to reveal the free diamine. We expect that this work will promote the further use of mixed aminal tethers in organic synthesis.     

Structural Manipulation of Aminal-crosslinked Polybutadiene for Recyclable and Healable Elastomers

Recently, increasingly growing efforts have been devoted to incorporating dynamic covalent bonds into covalently crosslinked networks to address the persistent trade-offs between chemical crosslinking and malleability. Herein, a series of dynamic aminal bond crosslinked polybutadiene rubbers(PAPB) are prepared by crosslinking aldehyde group-terminated polybutadiene rubber(APB) with piperazine. By varying the molecular weight of APB, the crosslinking density of PAPB is changed, which offers the platform to regulate the mechanical characteristics and dynamic properties. Specially, with the decrease of APB molecular weight, i.e. with the increase of crosslinking density, the modulus of PAPB gradually increases while the elongation at break conversely decreases, and the activation energy for network rearrangement initially decreases and then increases. The resultant PAPB exhibit vitrimer-like behaviors that can alter the network topologies at elevated temperatures without the loss of structural integrity through dissociative aminal exchange reactions, while the protic source can accelerate aminal dissociation and result in network dissolution even at room temperature. Due to the aminal exchange, PAPB are thermally malleable and can almost restore the original mechanical characteristics after recycling; besides, they are capable of healing at a relatively low crosslinking density.     

Fine-tuned aminal cleavage: a concise route to differentially protected enantiopure syn-alpha,beta-diamino Esters

A survey of routes for aminal cleavage of N-sulfinylimidazolidines has been carried out, and selective conditions to cleave the aminal moiety while preserving the sulfinamide group unaltered have been found. Thus, the treatment of enantiopure N-sulfinylimidazolidines with aqueous H(3)PO(4) in THF affords enantiopure N-sulfinyldiamino esters in excellent yields, while the presence of MeOH as cosolvent allows for the simultaneous removal of the sulfinamide group and aminal cleavage. The behavior of these substrates in a variety of chemical transformations has been explored.     

exo-Diastereoisomer of 10-aryl-1,4,7-triazabicyclo[5.2.1]decane as intermediary in specific derivatisation of triazacyclononane

Reaction of triazacyclononane (tacn) and aromatic aldehydes leads to aminal adducts, which exhibit only the exo configuration. In these aminal compounds, secondary amine function possesses a higher reactivity towards electrophilic reactants than the two nitrogen atoms linked to aminal carbon, giving rise to the specific derivatisation of tacn by different functionalised groups. Study of this behaviour also permits the access to a ditopic tacn–cyclam bicyclic polyamine.     

Recent results in insect pheromone chemistry

Pheromones are substances which are secreted to the outside by an animal, especially an insect, and received by a second individual of the same species, in which they release a specific reaction, for example, a definite behavior or developmental process. The name is derived from the Greek pherein (to bear, transmit) and hormon (impel, excite). Pheromones include, inter alia, sex attractants, warning substances, and “aggregation pheromones”. Many of these substances are effective at very low concentration. The insect pheromones are predominantly derivatives of long-chain, slightly branched hydrocarbons.     

Brønsted acid-catalyzed imine amidation

A new method for the Br?nsted acid-catalyzed addition of amide nucleophiles to imines to produce protected aminal products is described. Simple Br?nsted acids (phenyl phosphinic acid and trifluoromethanesulfonimide) were shown to be excellent catalysts, providing high yields of the aminal product. A catalytic asymmetric imine amidation using sulfonamides as nucleophiles was successful when a hindered biaryl phosphoric acid catalyst derived from 2,2'-diphenyl-[3,3'-biphenanthrene]-4,4'-diol (VAPOL) was used. Excellent yields and enantioselectivities were found in these additions (up to 99% ee).     

Novel approach to 3,3-dimethyl-4-morpholino-3,4-dihydrocoumarins via hetero-Diels–Alder reaction

A new four-step synthetic procedure has been developed to prepare 3,3-dimethyl-4-morpholino-3,4-dihydrocoumarins from substituted salicylaldehydes, morpholine, and isobutyraldehyde. It involves aminal formation, deamination, enamine formation, hetero-Diels–Alder reaction, hydrolysis, and oxidation. The aminal formation, subsequent one-pot domino deamination, enamine formation, and hetero-Diels–Alder reaction were achieved in microwave-assisted catalyst-free conditions. The following hydrolysis and oxidation steps, performed conventionally, gave quantitative yields.     

Asymmetric total synthesis of (-)-quinocarcin

(-)-Quinocarcin (1) has been synthesized in a longest linear sequence of 22 steps from 3-hydroxybenzaldehyde in 16% overall yield. The Pictet-Spengler reaction of L-tert-butyl-2-bromo-5-hydroxy phenylalanate (17), synthesized according to Corey-Lygo's enantioselective alkylation process, with benzoxyacetaldehyde (12) under mild acidic conditions afforded 1,3-cis tetrahydroisoquinoline 20 as an only isolable stereomer in 91% yield. The diazabicycle[3,2,1]-octane ring system of 28 was constructed by a silver tetrafluoroborate-promoted intramolecular Mannich reaction using amino thioether as a latent N-acyliminium species and tethered silyl enol ether as a nucleophile. Using amino thioether instead of aminal as a precursor of N-acyliminium was of high importance to the success of this otherwise disfavored 5-endo-Trig cyclization. A Hf(OTf)4-catalyzed (0.1 equiv) transformation of aminal to amino thioether was uncovered in the course of this study, allowing the conversion of tricyclic aminal 24 to amino thioether 25 to be realized in high yield. From the bridged tetracyclic compound 28, a sequence of oxidation of aldehyde to acid, global deprotection under hydrogenolysis conditions, and one-pot partial reduction of lactam to aminal/oxazolidine formation completed the total synthesis of the pentacyclic (-)-quinocarcine.     

Total synthesis and biological evaluation of pederin, psymberin, and highly potent analogs

The potent cytotoxins pederin and psymberin have been prepared through concise synthetic routes (10 and 14 steps in the longest linear sequences, respectively) that proceed via a late-stage multicomponent approach to construct the N-acyl aminal linkages. This route allowed for the facile preparation of a number of analogs that were designed to explore the importance of the alkoxy group in the N-acyl aminal and functional groups in the two major subunits on biological activity. These analogs, including a pederin/psymberin chimera, were analyzed for their growth inhibitory effects, revealing several new potent cytotoxins and leading to postulates regarding the molecular conformational and hydrogen bonding patterns that are required for biological activity. Second generation analogs have been prepared based on the results of the initial assays and a structure-based model for the binding of these compounds to the ribosome. The growth inhibitory properties of these compounds are reported. These studies show the profound role that organic chemistry in general and specifically late-stage multicomponent reactions can play in the development of unique and potent effectors for biological responses.