昆虫信息素缓释技术的研究进展

昆虫信息素是一类由昆虫个体释放于体外来调节或诱发同种其它个体行为与反应的化学物质。 近年来,应用昆虫信息素防治虫害是当前有机农业绿色防控的新技术之一。 与传统农药防治虫害相比,信息素具有高效、无毒、不产生抗药性以及对天敌无害的特点。 此外,昆虫信息素通常易降解且挥发性高。 因此,基于信息素的缓释技术引起了科研工作者的广泛关注,是涵盖化学、材料与农业的新兴交叉学科。 通过某种特定的方法或技术使昆虫信息素缓慢控制释放,既能有效防治虫害,减少农药使用,提升环境生态水平,同时也能促进区域环境化学品总量与农业成本的降低。 本文详细综述了昆虫信息素缓释技术的最新研究进展并对发展前景进行了展望。     

Asymmetric Synthesis of Spiroketals with Aminothiourea Catalysts

Chiral spiroketal skeletons are found as core structures in a range of bioactive compounds. These natural compounds and their analogues have attracted much attention in the field of drug discovery. However, methods for their enantioselective construction are limited, and easily available optically active spiroketals are rare. We demonstrate a novel catalytic asymmetric synthesis of spiroketal compounds that proceeds through an intramolecular hemiacetalization/oxy‐Michael addition cascade mediated by a bifunctional aminothiourea catalyst. This results in spiroketal structures through the relay formation of contiguous oxacycles, in which multipoint recognition by the catalyst through hydrogen bonding imparts high enantioselectivity. This method offers facile access to spiroketal frameworks bearing an alkyl group at the 2‐position, which are prevalent in insect pheromones. Optically active (2S,5S)‐chalcogran, a pheromone of the six‐spined spruce bark beetle, and an azide derivative could be readily synthesized from the bicyclic reaction product.     

Synthesis of heterocyclic bioregulators and semiochemicals

Chemistry and biology of oxygen heterocycles as insect pheromones are reviewed referring to exo-brevicomin, disparlure, japonilure and olean. Synthesis of koninginin A, a microbial metabolite, is discussed. Two azetidine alkaloids, penaresidin A and penazetidine A, were synthesized.     

Environmentally regulated abiotic release of volatile pheromones from the sugar-based oral secretions of caribflies

Abstract

We report an abiotic mechanism for the emission of volatile insect pheromones that is controlled by environmentally induced change in the physicochemical properties of the sugar-based release matrix. Male Anastrepha suspensa (Loew) (caribflies) mark mating sites on leaf surfaces by depositing oral secretions that contain sugar, as well as, γ-hydroxy acid and γ-lactone forms of the diastereomeric aggregation pheromones, epianastrephin and anastrephin. The γ-hydroxy acids extend emission over many days via aqueous equilibrium with the thermodynamically less preferred, but more volatile, γ-lactones (～100:1). A kinetic model, which supports a γ-lactone diffusion-limited rate, was generated and tested by measuring the effect of temperature and humidity under fixed and ambient atmospheric inputs, respectively. Results show that pheromone release from the markings occurs with a periodicity that parallels relative humidity and complements the daily pattern of the caribflies’ reproductive and aggregative activity. This study provides an example of a physicochemical-based inter-organism communication strategy that has been mechanistically linked to the abiotic environmental processing of volatile chemical signals. The exploitation of this natural connectivity will spur environmentally sustainable chemistries, particularly pheromone-based alternatives to insecticide application.     

α,ω-dicarbonyl 1,5-unsaturated isoprenoids with (Z)-and (E)-configured Δ-bonds in the synthesis of low-molecular-weight bioregulators

Syntheses carried out with participation of the author of terpenoids, polyprenols, prenylcarboxylic acids, insect pheromones, and juvenoids based on α,ω-dicarbonyl 1,5-unsaturated isoprenoid compounds with (Z)- and (E)-configurations, obtained by controlled ozonolysis of isoprene cyclic oligomers and polyisoprene rubbers, are considered. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2040–2051, November, 1999.     

Synthetic Applications of the Baylis–Hillman Reaction: Simple and Convenient Synthesis of Five Important Insect Pheromones

A simple and convenient synthesis of five important insect pheromones by means of Baylis–Hillman adducts is described, i.e., of (2E,4S)‐2,4‐dimethylhex‐2‐enoic acid ( 1 ), a mandibular‐gland secretion of the male carpenter ant in the genus Camponotus, of (+)‐(S)‐manicone ( 2 ) and (+)‐(S)‐normanicone ( 3 ), two mandibular‐gland constituents of Manica ants, and of (+)‐dominicalure‐I ( 6 ) and (+)‐dominicalure‐II ( 7 ), two aggregation pheromones of the lesser grain borer Rhyzopertha dominica (F). For the first time, the potential of the Baylis–Hillman chemistry for the stereoselective synthesis of trisubstituted olefins was successfully applied to the synthesis of these pheromone compounds.     

A Specific Blend of Drakolide and Hydroxymethylpyrazines: An Unusual Pollinator Sexual Attractant Used by the Endangered Orchid Drakaea micrantha

Bioactive natural products underpin the intriguing pollination strategy used by sexually deceptive orchids. These compounds, which mimic the sex pheromones of the female insect, are emitted in particular blends to lure male insect pollinators of specific species. By combining methods from field biology, analytical chemistry, electrophysiology, crystallography, and organic synthesis, we report that an undescribed β‐hydroxylactone, in combination with two specific hydroxymethylpyrazines, act as pollinator attractants in the rare hammer orchid Drakaea micrantha. This discovery represents an unusual case of chemically unrelated compounds being used together as a sexual attractant. Furthermore, this is the first example of the identification of pollinator attractants in an endangered orchid, enabling the use of chemistry in orchid conservation. Our synthetic blend is now available to be used in pollinator surveys to locate suitable sites for plant conservation translocations.     

Stereospecific 1,4-cis-hydrogenation of conjugated dienes,dienynes, and dienediynes catalyzed by chromium carbonyl complexes in stereocontrolled syntheses of physiologically active olefins

Synthesis of insect pheromones provides a good illustration of versatility, flexiblility, and practical convenience of the chromium carbonyl complexes-mediated 1,4-cis-hydrogenation of conjugated dienes as the tool for for stereocontrolled construction of di-, tri-, and tetrasubstituted olefins and nonconjugated dienes. A new strategy for synthesizing homoconjugated all-Z-dienes and trienes by hydrogenation of diene-alkyne conjugated systems using the same catalysts is proposed.     

Characterization of organic substrates bound to cross-linked polystyrenes by 13C NMR spectroscopy

The ¹³C NMR spectra of a wide variety of organic substrates bound to 2% cross-linked polystyrenes may be obtained routinely, provided the resins can be sufficiently swollen. The ¹³C chemical shifts of polymer-bound trityl alcohol, polymer-bound monotrityl ethers of the symmertrical diols HO (CH₂)_nOH (n=2, 4, 6, 7, 9 and 10), and some related intermediates in the solid phase synthesis of insect pheromones are presented. ¹³C shift additivity correlations, differing little from those in free trityl ethers, are drawn.     

Tellurium in organic synthesis: an approach to the synthesis of (Z,E)-dienic precursors of insect pheromones

A simple and straightforward route to (Z,E)-dienic precursors of insect pheromones was developed. The route features a cross-coupling of a (Z,E)-dienic telluride with an alkyl Lipshutz cuprate.     

Synthetic Studies towards Pheromones by Cyanide-Catalyzed Ring Transformation of α-Hydroxy-β-oxoesters to δ-Valerolactones

The cyanide-catalyzed ring-transformation of α-hydroxy-β-oxoesters to δ-lactones with exocyclic ester moiety is the key transformation for the preparation of racemic 5-hexadecanolide (15 % over nine steps) and 6-acetoxy-5-hexadecanolide (22 % over eight steps), two insect pheromones. The benzyloxycarbonyl moiety is transformed via the acid chloride to the undecanoyl side chain. After reduction of the ketone to the secondary alcohol, this functional group was either reduced via the chloro compound to furnish the 5-hexadecanolide. On the other hand, stereoselective reduction of the ketone gave secondary alcohol with the wrong relative configuration, which was established by X-ray single-crystal structure. Inversion was achieved by reaction of the methanesulfonate with cesium acetate yielding (R*,S*)-6-acetoxy-5-hexadecanolide with the relative configuration also present in the natural product.     

A versatile approach to the synthesis of 9(Z)-unsaturated acyclic insect pheromones from undec-10-enoic acid

A general approach to the synthesis of 9(Z)-unsaturated acyclic insect pheromones from undec-10-enoic acid was developed. The method comprises the conversion of the acid into undec-10-enyl acetate, shortening of its carbon chain to afford dec-9-enyl acetate (via 11-acetoxyundecanoic acid), and a two-step transformation of the latter into the key intermediate, dec-9-yn-1-ol, by sequential bromination—dehydrobromination. The elimination of two HBr molecules from the dibromide is effectively performed using Bu¹OK in the presence of dibenzo-18-crown-6 as the catalyst. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1637–1639, August, 1998.     

Studies Directed Towards a Practical Synthesis of Brevicomins (II)1 : A Novel Synthesis of 1, 5-Dimethyl-8-Oxobicyclo [3.2.1]octane-6-one

The recent interest in pheromones,² as means of controlling insect pests, has prompted us to examine syntheses which could be both simple and practical. We recently reported a three-step synthesis of brevicomin (3), the aggregating pheromone of the pine bark beetle, Dendroctonus brevicomis.³     

Fluoro-Analoga von Cycloheptadien-Pheromonen mariner Braunalgen: ungewöhnlich leicht verlaufende [3,3]-sigmatrope Umlagerung eines trans-di(alkenyl)-substituierten geminalen Difluorocyclopropans

Fluoro Analoga of Cycloheptadiene Pheromones of Marine Brown Algae: Exceptionally Facile [3,3]-Sigmatropic Rearrangement of a trans-Di(alkenyl)-Substituted Geminal Difluorocyclopropane The 3,3,-difluorocyclopropane-1,2-dicarbonyl compounds 9a and 9b are obtained by addition of difluorocarbene to methyl cinnamate or trans-stilbene followed by oxidative degradation of the phenyl rings(s) (Scheme 2). Compound 9b is a versatile building block for the synthesis of the di(alkenyl)-substituted geminal difluorocyclopropane 5 or the chrysanthemum ester 10b . Cyclopropane 5 is unstable at room temperature and rearranges to the 3,3,-difluorocyclohepta-1,4-diene 4 , an analog of the algal pheromone dictyotene ( 1 ; Scheme 3). The kinetic parameters of the [3,3]-sigmatropic rearrangement are determined. The data support the view that a geminal difluoro group within a cyclopropane weakens the distal bond.     

Regioselective Allylation of Ketones

In connection with our work concerning synthesis of insect pheromones,¹ we became interested in reports by Lorette and Howard² in which were described a method for preparing alpha-allyl ketones. These authors reported that diallyl ketals (4), available by exchange between a ketone (1), allyl alcohol and 2,2-dimethoxypropane, suffer acid-catalyzed elimination to yield intermediate allyl enol ethers (5/6) which undergo subsequent Claisen rearrangement to provide the alpha-allyl ketone products (2/3). The scheme on the following page summarizes the conversions involved.     

Synthese optisch aktiver 2-Methyl- und 2-Äthyl-1, 6-dioxaspiro [4.4]-nonan- und -[4.5]decan-Pheromone aus einem gemeinsamen chiralen Vorläufer

Synthesis of Optically Active 2-Methyl- and 2-Ethyl-1, 6-dioxaspiro [4.4]nonane- and -[4.5]decane Pheromones from a Common Chiral Precursor The versatility of the bromoepoxide 6 as chiral building block, which is readily available in both enantiomeric forms from malic acid, and which has previously been used for a vermiculine synthesis, is further demonstrated by the preparation of the title compounds 1, 3, 4 and 5 . Alkylation of 1,3-dithiane, first with the 1-ethoxyethyl-protected ω-chloroalcohols 8b or 9b and then with the (S)-(?)-bromoepoxide 6 , followed by oxirane opening with Selectride or methyl Gilman-reagent creates the desired carbon skeletons and functionality patterns 14–17 , in overall yields of 60–80%. Acetal and thioacetal hydrolyses directly furnish the spiroacetal target structures 1 and 3–5 as 3:2-diastereomeric mixtures; the E/Z-epimers 3 are separated by preparative GC. (Fig.).     

Acyclic stereocontrol via asymmetric [2,3]-Wittig rearrangement with high enantio- and erythro-selectivity and its use in the chiral synthesis of insect pheromones

Such an asymmetric [2,3]-Wittig variant that is both highly enantio- and erythro-selective is described within the context of the chiral synthesis of the insect pheromones, (3$\text{S}$, 4$\text{S}$)-4-methyl-3-heptanol and ($\text{S}$)-4-methyl-3-heptanone.     

Reglucosylation of the Benzoxazinoid DIMBOA with Inversion of Stereochemical Configuration is a Detoxification Strategy in Lepidopteran Herbivores

Benzoxazinoids are chemical defenses against herbivores and are produced by many members of the grass family. These compounds are stored as stable glucosides in plant cells and require the activity of glucosidases to release the corresponding toxic aglucones. In maize leaves, the most abundant benzoxazinoid is (2R)‐DIMBOA‐Glc, which is converted into the toxic DIMBOA upon herbivory. The ways in which three Spodoptera species metabolize this toxin were investigated. (2S)‐DIMBOA‐Glc, an epimer of the initial plant compound, was observed in the insect frass, and the associated glucosyltransferase activity was detected in the insect gut tissue. The epimeric glucoside produced by the insect was found to be no longer reactive towards plant glucosidases and thus cannot be converted into a toxin. Stereoselective reglucosylation thus represents a detoxification strategy in Spodoptera species that might help to explain their success as agricultural pests on benzoxazinoid‐containing crops.     

(4R,6R)-6-(hydroxymethyl)-4-methyltetrahydro-2H-pyran-2-one in the synthesis of polyfunctional compounds with the methyl-branched carbon skeleton

A simple and efficient asymmetrical synthesis was performed of a convenient bifunctional building block, methyl (R)-5,5-dimethoxy-3-methylpentanoate and its (S)-enantiomer. The possibility was shown of its application to the synthesis of insect pheromones.     

A portable gas chromatograph with simultaneous detection by mass spectrometry and electroantennography for the highly sensitive in situ measurement of volatiles

Mating disruption is a sustainable method for the control of insect pests, involving the release of synthetic sex pheromones that disrupt the olfactory localization of females by males. However, the development and refinement of this strategy is hampered because current instruments lack the sensitivity to detect volatile organic chemicals in the field, and portable electroantennograms produce non-comparable relative units and distorted results in the presence of plant volatiles. To address the demand for more sensitive instruments that are suitable for the rapid in situ detection of airborne pheromones, we have developed a portable, automated needle trap device connected to a gas chromatograph, mass spectrometer, and electroantennographic detector (NTD-GC-MS/EAD) suitable for field applications. We tested the instrument by measuring the concentration of the sex pheromone (E,Z)-7,9-dodecadienyl acetate, which is used to disrupt the mating of the European grapevine moth Lobesia botrana (Lepidoptera: Tortricidae). Our data confirm that the instrument generates highly reproducible results and is highly sensitive, with a detection threshold of 3 ng/m³ (E,Z)-7,9-dodecadienyl acetate in outside air.