Insect Antifeedants Research Articles

Chemistry of insect antifeedants from Azadirachta Indica (part 18): Demethylation and methylation of the C-8 position of the decalin portion of azadirachtin

The degradation of azadirachtin ( 1) to the demethylated decalin 4 and the subsequent remethylation to the protected fragment 5 are described. The crucial steps in the degradation sequence were the decarbonylation of 14 and the selective removal of the hydroxy group at C8 in 16. Reaction of the silyl enolether of 4 with Eschenmoser's salt and subsequent reduction of enone 24 gave 5.

ChemInform Abstract: Diastereoselective Synthesis of a Limonoid Model Related to the Insect Antifeedant Genudin.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Diastereoselective Synthesis of a Limonoid Model Related to the Insect Antifeedant Genudin

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiastereoselective Synthesis of a Limonoid Model Related to the Insect Antifeedant GenudinMarc Renoud-Grappin, Corinne Vanucci, and Gerard LhommetCite this: J. Org. Chem. 1994, 59, 14, 3902–3905Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published inissue 1 July 1994https://doi.org/10.1021/jo00093a023RIGHTS & PERMISSIONSArticle Views1058Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (561 KB) Get e-Alerts Get e-Alerts

Oxirane-opening reactions of some 6,19-oxygenated 4α,18- epoxy- neo-clerodanes isolated from Teucrium. Biogenesis and antifeedant activity of their derivatives

Some 4α, 18-epoxy- neo-clerodane diterpenoids possessing oxygenated functions at the C-6 and C-19 carbons have been subjected to oxirane-opening reactions with several reagents obtaining chlorohydrins, 4-hydroxy-6,18-ethers, 4-hydroxy-18- O-methyl- and 18- O-acetyl derivatives, allylic C-18 primary alcohols and 4,6,18 and 4,6,19- orthoacetates. These results revealed that the functionality at C-6 and its stereochemistry determine the course of the reaction and affect the retention or inversion of the configuration at the C-4 asymmetric centre. In the light of these reactions, a hypothesis on the biogenetic pathway of some neo-clerodane diterpenoids isolated from Teucrium species is proposed. Moreover, useful criteria for establishing the stereochemistry at C-4 in these derivatives, as well as the unambiguous assignment of the structure of montanin E by an X-ray diffraction analysis and the results achieved in the biological assay as insect antifeedants of several non-natural neo-clerodane derivatives are also reported.

Potential plant products with insect antifeedant properties

Abstract The present review deals with various botanical, chemical and biological aspects of naturally-occurring insect antifeedants. Insect antifeedants play a significant role in host plant selection. Extensive work has been done on plant products in pest control and many of these compounds have been identified belonging to different plant classes during the past five years. Some developing research trends in the utilization of plant products for pest control are reviewed with their possible role in agricultural pest management and in pharmaceutical application. A complete literature on plant-insect interaction is available on request.

Some remarkable reactions of the diterpene eriocephalin: Neo-clerodane derivatives with insect antifeedant activity

Base-catalyzed reaction of the neo-clerodane diterpenoid eriocephalin ( 1) gave the derivatives 3 and 4. The formation of these compounds implies an elimination of the C-19 carbon atom of 1 as formaldehyde by a reaction and, in the case of 4, subsequent reaction of this formaldehyde with the 18-alkoxide intermediate followed by an intramolecular and stereoselective 1,4-addition of the resulting C-18-oxa-methylene alkoxide. Treatment of the derivative of eriocephalin 9 with base yielded transacetylation and hydrolysis products ( 10–14), with inversion of the configuration at the C-20 asymmetric centre. Mechanistic aspects of these transformations and the results achieved in the biological assay as insect antifeedants of these neo-clerodane derivatives are also reported.

Chemical transformations of some neo-clerodanes isolated from Teucrium: Effect on the antifeedant activity

The neo-clerodane diterpenes montanin C, teucrin P 1 and teupolin III have been subjected to a series of chemical transformations to give α, β-unsaturated 15,16- and 16,15-γ-lactones, 13,14,15,16-tetranor- neo-clerodanes, chlorohydrins, vinyl chlorides, and amine, 1-pyrroline and 2-pyridazoline derivatives. These compounds have been assayed as insect antifeedants against larvae of Spodoptera littoralis and the structure-biological activity relationships are discussed.

Chemistry of insect antifeedants from Azadirachta indica (Part 17): Synthesis of model compounds of azadirachtin. Unusual effect of remote substituents on the course of the oxidative ring contraction reaction.

The synthesis of model compounds of azadirachtin containing the tetrahydrofurancarboxylate hemiketal functional group was achieved. The course of the oxidative ring contraction reaction that was used to form this functional group was observed to be unusually sensitive to the nature of substituents remote from the reactive centre.

Isolation of a New Insect Antifeeding Azadirachtin Derivative from Okinawan Melia azedarach Linn

A new azadirachtin-type insect antifeedant, 1-cinnamoyl-3-acetyl- 11-methoxymeliacarpinin, was isolated from the stem bark of Okinawan Melia azedarach Linn

Chemistry of insect antifeedants from Azadirachta indica (Part 16): Synthesis of several derivatives of azadirachtin containing fluorescent or immunogenic reporter groups

Dinitrophenylamino, dansyl, and biotin groups have been covalently attached to several azadirachtin derivatives via a linker group to give fluorescent or immunogenic compounds that generally retain the biological properties of azadirachtin. These compounds are potential tools for the determination of the mechanisms of azadirachtin's action in living systems.

Potential of natural products as insect antifeedants

AbstractInsect antifeedants are the substances that play a significant role in host plant selection by phytophagous insects. Extensive work has been done on natural antifeedants and a large number of these compounds have been identified belonging to different classes during the past decade. The present article deals with various chemical and biological aspects of insect antifeedants and with their possible role in insect pest management.

ChemInform Abstract: Chemistry of Insect Antifeedants from Azadirachta indica. Part 12. Use of Silicon as a Control Element in the Synthesis of a Highly Functionalized Decalin Fragment of Azadirachtin.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The synthesis of dithyreanitrile

Abstract An efficient synthesis of dithyreantrile ( 1 ), a novel insect antifeedant, is presented.

An insect antifeedant limonoid from seed of khaya ivorensis

A novel limonoid which is an insect antifeedant has been isolated from a methanolic extract of seeds of Khaya ivorensis. Its structure was determined on the basis of one and two-dimensional NMR. spectroscopy and chemical evidence.

C-alkylations of indoles and pyrroles with α-chloro sulfides on an alumina surface: a short synthesis of dithyreanitrile

Alumina-mediated C-alkylations of indoles and pyrroles with α-chloro sulfides have been examined. Thus, a mixture of indoles 1 and the α-chloro sulfides 2 or 3, on treatment with neutral alumina, gave the ethyl indol-3-ylacetates 5 and the corresponding acetonitriles 6, respectively. A similar reaction of the chloride 4 with 7-methoxyindole provided direct access to dithyreanitrile 7h, which is an insect antifeedant. The pyrrole 10 was also allowed to react with the α-chloro sulfides 2 and 3 to afford the 2-substituted products 11 and 12, respectively. On the other hand, the reactions of skatole 14 with 2 and 3 gave the 2-alkylation products 15 and 16, respectively, but in low yields. However, 2,3-dimethylindole 17 reacted smoothly with 2 and 3 to give the indolenines 18 and 19, respectively. The reaction of 2,5-dimethylpyrrole 25 with 2 afforded the 2,2,5-trisubstituted 2H-pyrrole 26 as a major product along with the 2,3,5-trisubstituted 1H-pyrrole 27. Some chemical transformations of the products 5, 18 and 26 are also described.

Chemistry of insect antifeedants from Azadirachta indica(part 12): use of silicon as a control element in the synthesis of a highly functionalized decalin fragment of azadirachtin

A diastereoselective synthesis of a highly functionalized decalin fragment 61 of the insect antifeedant azadirachtin 1 is described. An intramolecular Diels–Alder reaction of triene 15 and subsequent intramolecular aldol reaction were employed to assemble the basic carbon skeleton. A high degree of stereocontrol in the cycloaddition step was achieved by using a dimethyl(phenyl)silyl group to effect endo-selectivity. The silyl group enabled further diastereoselective elaboration and later stereospecific introduction of C(3) hydroxy functionality through oxidation with peracid. Both enantiomers of the intermediate alcohol 40 were obtained by optical resolution. The C(9)–C(10) tetrahydrofuran hemiketal moiety was introduced using a novel 6→5 ring-contraction protocol with initial formation of the δ-lactone 49 by an intramolecular Michael addition. Subsequent α-hydroxylation and methanolysis furnished the tetrahydrofuran hemiketal 50, which was converted in two steps into the fully protected enantiopure target molecule 61. Single-crystal X-ray analyses of compounds 18, 50, and (+)-53 have been carried out and the absolute configuration of compound (+)-53 determined

Synthesis of limonoid model insect antifeedants through stereoselective aldol addition reactions

The aldol condensation of 3-furaldehyde and enol silanes or enolates(Li,Mg and Ti) of 2,6-dimethyl- and 2,2,6-trimethylcyclohexanones has been investigated.The lithium enolate of 2,6-dimethylcyclohexanone showed good facial and diastereoselectivity as did the magnesium enolate of 2,2,6-trimethylcyclohexanone.These results were applied to the preparation of limonoid model compound by a short and selective route

Chemistry of insect antifeedants from Azadirachta indica (part 11): Characterisation and structure activity relationships of some novel rearranged azadirachtins.

Several novel rearrangement reactions of the natural product azadirachtin and related derivatives have been characterised using a combination of x-ray crystallographic and high field nmr techniques. The insect antifeedant properties of these and a number of C7 modified compounds have been investigated.

Chemistry of insect antifeedants from azadirachta indica (Part 9): oxidative reactions of azadirachtin derivatives leading to C8-C14 bond cleavage.

A novel macrocyclic carbonate (4) was obtained by pyridinum chlorochromate oxidation of an azadirachtin derivative (3). This underwent efficient C8-C14 bond cleavage via a retro-Aldol reaction to give a highly functionalised decalin derivative (5) with potential for use in relay synthesis of azadirachtin.

Chemistry of insect antifeedants from Azadirachta indica (Part 10): synthesis of a highly functionalised decalin fragment of azadirachtin.

The synthesis of a highly functionalised decalin fragment (2) of the antifeedant azadirachtin (1) is described. A silyl group was employed to control the stereoselectivity of several key steps and to introduce C3 hydroxyl functionality. A novel ring contraction strategy afforded the inherent hemiketal unit.