肟醚(酯)农药研究进展

综述了对肟醚(酯)农药的研究进展,介绍了其结构特点、生物活性、研究现状、立体异构及立体有择合成等方面的内容。     

萜烯肟醚衍生物的合成及生物活性研究

探讨了萜烯肟醚的合成方法,合成了8个新型萜烯肟醚类化合物,并经元素和核磁确证结构.初步生物活性测试显示：部分化合物具有较好的杀菌活性.     

肟醚类拟除虫菊酯立体有择合成

某些烷基芳基酮肟苯氧基苄醚化合物具有拟除虫菊酯杀虫特性。我们曾合成以下结构肟醚类化合物,研究其合成方法、结构特性及生物活性。     

具有生物活性的肟醚类化合物的研究进展

肟醚化合物具有优良的杀虫、杀菌及除草活性,不少品种还具有低毒、低残留等优点。目前该类化合物的分子设计和合成及生物活性研究是农药创制的热点之一。按照不同的结构和生物活性进行分类,概述了近年来肟醚类化合物的研究进展,并对它的发展趋势、应用前景作了进一步展望。     

新型具有含硫肟醚基的苯甲酰脲类化合物的合成及其杀虫活性研究

通过含硫不饱和肟醚与2，6-二氟苯甲酰异酯反应，合成了9个新的具有含硫肟醚基的苯甲酰脲类化合物，其结构均经^1HNMR、IR、LC／MS及元素分析确证，检测结果表明部分化合物表现出很高的杀虫活性。     

含吡啶的Strobilurin类化合物的研究进展——肟醚乙酸酯和肟醚乙酰胺类

简要叙述了含肟醚乙酸酯和肟醚乙酰胺的吡啶strobilurin类化合物近年来的研究进展，并介绍了其化学结构和生物活性。     

含吡啶的strobilurin类化合物的研究进展——肟醚乙酸酯和肟醚乙酰胺类

本文简要叙述了含肟醚乙酸酯和肟醚乙酰胺的吡啶strobilurin类化合物近年来的研究进展，主要介绍其化学结构和生物活性。     

含吡啶环肟醚化合物的合成及生物活性

研究了含吡啶环的肟醚化合物的合成及所合成化合物的生物活性     

(E)-2-(甲氧基亚胺基)-2-甲基苯乙酸甲酯合成方法综述

(E)-2-(甲氧基亚胺基)-2-甲基苯乙酸甲酯(简称肟醚)是合成肟菌酯、烯肟菌胺、醚菌酯等甲氧基丙烯酸酯类杀菌剂的关键中间体,介绍了目前已报道的合成肟醚的各种合成路线,对其进行了初步评价,以期找到适合工业化的较佳合成工艺。     

羟基香茅醛肟及其烷基醚的合成与除草活性

将羟基香茅醛(1)与盐酸羟胺反应合成羟基香茅醛肟(2),再与溴代烷反应制得4种羟基香茅醛肟烷基醚(3a～3d),用GC-MS、IR和NMR对产物结构进行了表征.采用平皿法测定了羟基香茅醛肟及其烷基醚在不同浓度下对一年生黑麦草生长的抑制作用,结果表明:化合物3b(0.31 mmol/L)、化合物3c(0.63 mmol/...     

Investigations on the stereochemistry and polymerization of the 1,3-dioxolane derivatives. VIII

Summary The polymerization of 1,3-dioxolane initiated by a new type of initiator — trisubstituted 1,3-dioxolan-2-ylium salts was studied. It was found that the rate of monomer consumption depends on the kind of substituents and anions as well as on the geometrical structure of the isomeric salt used. The dioxolenium salts with an aliphatic substituent at C-2 and with stable anions are more active then salts with an aromatic substituent or those having unstable anions. In all these cases the cis isomers are more active than respective trans salt isomers.     

Autoxidation of methyl linoleate. Separation and analysis of isomeric mixtures of methyl linoleate hydroperoxides and methyl hydroxylinoleates

The mixture of conjugated diene hydroperoxide isomers obtained from autoxidation of methyl linoleate was separated by high performance liquid chromatography (HPLC). Four major isomers were obtained from adsorption chromatography and identified as the 9 and 13 positional isomers having thetrans-trans andcis-trans configurations. The latter geometrical isomers have thetrans double bond adjacent to the hydroperoxide group. The hydroxy compounds (methyl hydroxylinoleates) obtained from the hydroperoxides by NaBH₄ reduction were similarly separated but with improved resolution. This is the first instance of the complete separation of these compounds and provides a rapid method for their analysis. Unlike adsorption chromatography, reversed-phase chromatography separates the mixtures only according to the geometrical isomerism of the double bonds and not according to the position of the hydroxy or hydroperoxide function.     

trans-Polyunsaturated fatty acids in French edible rapeseed and soybean oils

The fatty acid compositions of rapeseed and soybean oils marketed in France have been determined by gas liquid chromatography on a fused-silica capillary column coated with a 100% cyanopropyl polysiloxane stationary phase. Under the operating conditions employed, methyl esters of linolenic acid geometrical isomers could be separated and quantitated easily without any other complementary technique. With only one exception, all samples under study (eight salad oils and five food samples) contain geometrical isomers of linolenic acid in measurable, although variable, amounts. Totaltrans-18:3 acids may account for up to 3% of total fatty acids. This value corresponds to a degree of isomerization (percentage oftrans isomers relative to total octadecatrienoic acids) of 30%. Examination of our data indicates that the distribution pattern of linolenic acid geometrical isomers does not depend on the degree of isomerization. The two main isomers always have thec,c,t and thet,c,c configurations. These isomers occur in the almost invariable relative proportions of 47.8±1.7% and 41.1±1.0%, respectively. The third mono-trans isomer is present in lower amounts−6.5±0.7%. The only di-trans isomer that can be quantitated with sufficient accuracy is thet,c,t isomer (4.9±1.5%). Mono-trans isomers of linoleic acid are also present in these oils. However, their maximum percentages are lower than those determined for linolenic acid geometrical isomers. In the oils showing the highest degrees of isomerization,trans isomers of linoleic acid account for 0.5% (rapeseed oils) and 1% (soybean oils) of total fatty acids. Taking into account all data, it would appear that the probability of isomerization of linolenic acid is about 13–14 times that of linoleic acid.     

An improved preparation of some insect sex attractants: Synthesis and separation of geometrical isomers by formation of urea complexes

Wittig condensations of aldehydes or ketones with phosphonium salts are frequently used methods for the syntheses of straight-chain or branched alkenes. Suitable choice of reaction conditions may provide the desired geometrical isomer as reaction product. However, we have found that mixtures of geometrical isomers can be conveniently separated on a large scale by the relatively inexpensive method of urea inclusion complex formation. The recovery of both isomers from the separation procedure is almost quantitative. Urea inclusion complexes are formed preferentially withE isomers. Formation of the inclusion complex is affected by the skeletal structure and by the nature of the terminal functional group. By applying this method of separation at a convenient stage, several insect pheromones were prepared without the necessity of a stereoselective step. The technique was used for syntheses of (Z)-11-hexadecenal and (Z)-9-tetradecenal (components of theHeliothis virescens pheromone) and for the synthesis of candidate attractants possessing a trisubstituted double bond.This work was conducted under a Cooperative Agreement between the University of Maryland and the Agricultural Research Service.Mention of a commercial product in this paper does not constitute an endorsement of this product by the USDA.     

Hydrogenation and Isomerization of Methyl 9-Octadecenoates

Both methyl cis-9-octadecenoate and methyl trans-9-octadecenoate (commonly known as methyl oleate and methyl elaidate) were hydrogenated at operating conditions within the following ranges: 100–140°C, 1.7–14.6 at and 0.05–0.14% nickel catalyst. Correlations were developed for both geometrical and positional isomers as a function of iodine value. Decreases in pressure or increases in temperature resulted in a relatively greater increase in the amounts of positional isomers as compared to geometrical isomers. The rates of isomerization were found to vary between 0.7 to 2.5 times the rates of hydrogenation for hydrogenation runs with methyl cis-9-octadecenoate. The ratio between these two rates increased with higher temperatures or lower pressures. The rates of hydrogenation were compared for methyl cis-9-octadecenoate, methyl trans-9-octadecenoate, and cottonseed oil. Hydrogenation rate constants decreased in the following order: methyl trans-9-octadecenoate, methyl cis-9-octadecenoate, and cottonseed oil. The induction period that occurred only when a new catalyst was used depended on the temperature, pressure, and fatty feedstock being hydrogenated. The catalyst was activated to a considerable extent during the induction period.     

Further studies on artificial geometrical isomers of α-linolenic acid in edible linolenic acid-containing oils

Fifteen samples of commercial edible soybean and rapeseed oils (and mixtures of these) from Belgium, Great Britain and Germany have been analyzed for theirtrans-polyunsaturated fatty acid content. Only one sample out of the 13 refined samples, and the two cold-pressed samples, contained trace amounts oftrans isomers. Others contained between 1 and 3.3% of their total fatty acids as geometrical isomers of linoleic and linolenic acids. The degree of isomerization (DI) of linolenic acid varied between 10.5 and 26.9%. Combining results obtained in this study together with corresponding data for French oils (totalling 21 samples) indicates that the relative percentages of individual linolenic acid geometrical isomers depend on linolenic acid DI. Relationships linking these parameters could be approximated by straight lines, at least for DIs lying between 9 and 30%. Extrapolation to DI=0 suggests that the relative probabilities of isomerization of double bonds in positions 9, 12, and 15 are 41.7, 6.1 and 52.1%, respectively, at the very beginning of the isomerization reaction. At that time, the probability of a simultaneous isomerization of double bonds in positions 9 and 15 is close to zero. Thet,c,t isomer is apparently formedvia thec,c,t and thet,c,c isomers, the former being somewhat more prone to a second geometrical isomerization than the latter. The relative proportion of thec,t,c isomer is practically independent from the DI, at least between 9 and 30%, which would suggest that this isomer is an “end-product” of thecis-trans isomerization reaction.     

Autoxidation of methyl linolenate: Analysis of methyl hydroxylinolenate isomers by high performance liquid chromatography

The mixture of methyl hydroxylinolenates obtained by reduction of the hydroperoxide isomers formed by autoxidation of methyl linolenate was resolved by high performance liquid chromatography into eight major components. These are positional isomers with the hydroxyl group at positions 9, 12, 13, and 16. Two geometrical isomers of each positional isomer are present; these differ in the configuration of the conjugated double bonds (cis-trans andtrans-trans). Autoxidation of methyl linolenate is regioselective and favors the formation of positional isomers 9 and 16.     

Autoxidation of linoleic acid and behavior of its hydroperoxides with and without tocopherols

The autoxidation of linoleic acid dispersed in an aqueous media and the effect of α-, γ- and δ-tocopherols were studied. The quantitative analysis of the hydroperoxide isomers (13-cis,trans; 13-trans,trans; 9-trans,cis; 9-trans,trans) by direct high-performance liquid chromatography exhibited a prooxidant activity of α-tocopherol at high concentration (3.8% by weight of linoleic acid). On the other hand, α-tocopherol at lower concentrations (0.38 and 0.038%) and γ- and δ-tocopherols at high concentration (3.8%) were antioxidant. Furthermore, the addition of tocopherols modified the distribution of the geometrical isomers. The formation of thetrans,trans hydroperoxide isomers was completely inhibited by the highest concentration of the three tocopherols independently of their antioxidant or prooxidant activity and only delayed by the lower concentrations of α-tocopherol. The addition of tocopherols to hydroperoxide isomers reduced the decomposition rate of these isomers in the order α-tocopherol < γ-tocopherol < δ-tocopherol for thecis,trans hydroperoxide isomer and α-tocopherol ≪ γ-tocopherol ⋍ δ-tocopherol for thetrans,trans hydroperoxide isomer. With these hydroperoxides, as during linoleic acid autoxidation, α-tocopherol was completely oxidized whatever its initial concentration, while γ-tocopherol underwent partial oxidation and δ-tocopherol was practically unchanged.     

GLC and TLC analysis of isopropylidene derivatives of isomeric polyhydroxy acids derived from positional and geometrical isomers of unsaturated fatty acids

Gas-liquid chromatography (GLC) and thin-layer chromatography (TLC) were used to investigate the isomeric positional geometrical isopropylidene derivatives of nine isomeric dihydroxy esters, four isomeric methyl 9,10-12-trihydroxystearates, and eight isomeric methyl 9,10-12,13-tetrahydroxystearates prepared from unsaturated fatty acids. The isopropylidenes derived fromcis andtrans monounsaturated fatty acids were easily separated on both polar and nonpolar columns. Positional isopropylidenes derived from positional isomers of monounsaturated fatty acids were not separated on either liquid phase but were resolved by TLC. Four of the eight isomeric isopropylidenes derived from the four geometrical isomers of linoleic acid were resolved on the polar column; the other four isomers eluted as a single peak. The four isomeric isopropylidene-trifluoroacetate derivatives derived from ricinoleic and ricinelaidic acids were also resolved on the polar column. GLC analyses were carried out with liquid phases of ethylene glycol succinate methyl silicone polymer (EGSS-X) and methyl silicone polymer (SE-30) packed columns. Isopropylidenes, in addition to their applicability for the resolution of polyhydroxy acid mixtures, are particularly useful for the determination of double bond positions and geometrical configurations of fatty acids without cleavage. Under contract with the U. S. Atomic Energy Commission.     

Geometrical and positional isomer content of the monounsaturated fatty acids from various rat tissues

The percentage distribution of the geometrical and positional isomers in the hexadecenoates and octadecenoates isolated from triglycerides, phosphatidylch olines, and phosphatidylethanolamines of brain, heart, kidney, liver, lung, muscle, spleen, and adipose tissues from normal rats maintained on a laboratory diet has been determined. All of the octadecenoates and most of the hexadecenoates from the lipid classes of all the tissues consisted of more than 95%cis isomers. Generally, palmitoleic was the predominant hexadecenoate, but many of the tissue phospholipids contained relatively high percentages of the Δ6 and Δ7 isomers. Oleate and vaccenate were the predominant octadecenoates in all tissues. Except for brain and adipose tissues, the oleate to vaccenate ratios differed for each lipid class, as well as between most tissues. In contrast to the monoenes of the phospholipids, the triglyceride monoenes exhibited the same approximate: percentage composition; percentage of geometrical isomers; and percentage distribution of hexadecenoate and octadecenoate positional isomers. These data add to our basic information about the percentage distribution of geometrical and positional isomers of naturally occurring unsaturated fatty acids in the major lipid classes of various normal tissues. Some new concepts were advanced as possible explanations to some of the observed positional isomer distributions.