Synthesis and stereochemical assignment of trans-2-methyl-2-pentenoic acid and the corresponding esters, aldehydes, and alcohols

Chan, Kai Chiu; Jewell, Richard; Nutting, William H.; Rapoport, Henry

doi:10.1021/jo01273a004

Cited by 105 publications

(21 citation statements)

References 2 publications

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“…The 8-oxocitrals are relatively unstable, and they slowly isomerize upon standing. Only the C-6 double bond isomerizes, thus, showing the higher reactivity of 8-oxocitral at this position (Chan et al 1968). Before performing the bioassays (see below), the relative proportion of the mixtures c3 + c4 had already changed from 3:1 to 1:1 and from 1:9 to 1:4.…”

Section: Chemical Analyses and Synthesesmentioning

confidence: 98%

Defense by Volatiles in Leaf-Mining Insect Larvae

et al. 2009

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The defense strategy of an insect toward natural enemies can include a trait that appears at first sight to contradict its defensive function. We explored phylogeny, chemistry, and defense efficiency of a peculiar group of hymenopteran sawfly larvae where this contradiction is obvious. Pseudodineurini larvae live in leaf mines that protect them from some enemies. Disturbed larvae also emit a clearly perceptible lemon-like odor produced by ventral glands, although the mine hampers the evaporation of the secretion. The mine could also lead to autointoxication of a larva by its own emitted volatiles. Citral was the major component in all Pseudodineurini species, and it efficiently repels ants. We conclude that full-grown larvae that leave their mine to pupate in the soil benefit from citral by avoiding attacks from ground-dwelling arthropods such as ants. In some species, we also detected biosynthetically related compounds, two 8-oxocitral diastereomers (i.e., (2E,6E)- and (2E,6Z)-2,6-dimethylocta-2,6-dienedial). Synthetic 8-oxocitral proved to be a potent fungicide, but not an ant repellent. The discrete distribution of 8-oxocitral was unrelated to species grouping in the phylogenetic tree. In contrast, we discovered that its presence was associated with species from humid and cold zones but absent in species favoring warm and dry environments. The former should be protected by 8-oxocitral when faced with a fungal infestation while crawling into the soil. Our work shows the importance of integrating knowledge about behavior, morphology, and life history stages for understanding the complex evolution of insects and especially their defense strategies.

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Section: Chemical Analyses and Synthesesmentioning

confidence: 98%

Defense by Volatiles in Leaf-Mining Insect Larvae

et al. 2009

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“…The E stereochemistry for 4 was indicated from the nmr spectrum because a signal for the unsaturated aldehyde proton was seen at 9.4 ppm. A signal for the aldehyde proton of the Z isomer would appear downfield near 10 ppm if it was present in detectable amounts (6,19). The nmr analysis of the crude reaction product mixture gave no evidence for the presence of the Z aldehyde, so it was concluded that this reaction had proceeded with high (> 95%) stereoselectivity.…”

Section: +Hoc(ch)c-chi(mentioning

confidence: 99%

“…Alternatively, 7 (75-95% purity) was obtained in 50-80% yields by preparative hplc using a solvent system of 4% ethyl acetate in methylene chloride: bp 72-76°C (0. (19). During ci-ms analyses, ions at tnlz 215 and 189 were monitored but these ions, which correspond to quasimolecular ions for P-hydroxy esters of 3 and 7, were absent.…”

Section: -(13-diorolan-2-yl)-4-1~1ethyl-i-pentanal(7)mentioning

confidence: 99%

Synthesis and characterization of some oxidized derivatives of citronellal ethylene acetal

Taylor¹

1982

Can. J. Chem.

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Agricirlf~rre Cot~nt/a Resenrch Smrion, Lerhbrirlge, Alm.. C a t z~c l~ TIJ 4B1 Received October 26, 1981 WESLEY G. TAYLOR. Can. J. Chem. 60, 1847Chem. 60, (1982.Three pairs of geometrical isomers corresponding to allylic monooxidation products of the trisubstituted olefin, citronellal ethylene acetal(3), were synthesized. These compounds were the E and Z isomers of 7-(1,3-dioxolan-2-yl)-2,6-dimethyl-2-hepten-1-01, -1-al, and -I-oic acid (methyl ester), precursors for identifying the biodegradation products from citronellal and some of its derivatives. The E aldehyde (4) was obtained from 3 by the Sharpless procedure with catalytic quantities of seleniumdioxide. The E ester (5) and E alcohol (6) were prepared in high isomeric purity (97-99%) from 4 with activated manganese dioxide and sodium borohydride, respectively. Selective ozonolysis of the isobutenyl group in 3 gave 5-(1,3-dioxolan-2-y1)-4-methyl-I-pentanal (7). Under the conditions used, ozone did not react with the ethylene acetal group. Acetal aldehyde (7) was stereoselectively converted to the Z alcohol (8) by a Wittig reaction. Manganese dioxide oxidation of 8(98-99% Z isomer) to the Z aldehyde (9) and of9 to the Z ester (10) was accompanied by partial Z to E isomerization. The distribution of E and Z isomers in crude reaction mixtures was determined by gas chromatography with a glass capillary column or by proton magnetic resonance spectroscopy.WESLEY G. TAYLOR. Can. J. Chem. 60, 1847Chem. 60, (1982.On a synthetise trois paires d'isomeres geomCtriques qui proviennent de la mono-oxydation allylique de I'olCfine trisubstitue, l'acetal ethylenique du citronellal (3). Ces composes sont les isomeres E et Z du (dioxolanne-1,3 yl-2)-7 dimethyl-2,6 heptene-2 01-1, de l'aldehyde (al-I) et de I'acide (oique-1 sous forme d'ester mkthylique) correspondants qui sont les precurseurs dans I'identification des produits de biodegradation du citronellal et de quelques-uns de ses dkrivks. On a obtenu l'aldehyde E (4) a partir du compose (3) en faisant appel au procede de Sharpless avec des quantites catalytiques de bioxyde de sCICnium. On apripark l'ester E-(5) et I'alcool E-(6) avec une grande purete isomerique (97-99%) en soumettant respectivement le compose 4 a une oxydation par le bioxyde manganese active et une reduction au borohydrure de sodium. L'ozonolyse selective du groupe isobutenyle du compose 3 donne le (dioxolanne-1,3 yl-2)-5 methyl-4 pentanal-l (7). Dans les conditions utilisees, I'ozone ne rtagit pas avec I'acetal ethylenique. On a transforme d'unefa~on stCreosClective I'acCtal-aldehyde 7en alcool Z (8) par une reaction de Wittig. L'oxydation du compose 8 (isomere Z a 98-99%) en aldehyde Z (9) et du compose 9 en l'ester Z (10) par le bioxyde de manganese s'accompagne d'une isomerisation partielle de Z en E. On a determine la distribution des isomkres E et Z des melanges rtactionnels bruts par chromatographie en phase vapeur avec un colonne capillaire en verre ou par la spectroscopie de rmn du proton.[Traduit par le journal]

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“…1), were in favor of a trisubstituted C¼C moiety conjugated with the ester C¼O. The (E)-geometry of the conjugated C¼C bond was established by the chemical shift of the olefinic H-atom in b-position (d(H) 6.79) [16] and also by a cross-peak between the signals of Me(9'') and CH 2 (4'') in the NOESY plot. The 1 H-NMR spectrum further exhibited three downfield ABC-type dd at d(H) 5.88 (J ¼ 17.2, 10.8 Hz, HÀC(7'')), 5.20 (J ¼ 17.2, 1.4 Hz, H a ÀC(8'')), and 5.04 (J ¼ 10.8, 1.4 Hz, H b ÀC(8'')) indicating the presence of a terminal C¼C bond.…”

mentioning

confidence: 99%

Chromenone Glucosides Acylated with Monoterpene Acids from the Leaves of Eucalyptus camaldulensis var. obtusa

Begum

Farhat

Siddiqui

2011

Helvetica Chimica Acta

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Three new chromenone glucosides acylated with monoterpene acids, eucamaldusides A (1), B (2), and C (3), were isolated from the leaves of Eucalyptus camaldulensis var. obtusa, together with the five known compounds ursolic acid lactone, obtusilin, b-sitosterol glucoside, 4-hydroxybenzoic acid, and cypellocarpin C. The structures of the new compounds were established by exhaustive 1D-and 2D-NMR spectroscopic studies. Their configuration was determined by measuring the [a] D of the known methyl esters of the monoterpene acids obtained by methanolysis of 1 -3.

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Synthesis and stereochemical assignment of trans-2-methyl-2-pentenoic acid and the corresponding esters, aldehydes, and alcohols

Cited by 105 publications

References 2 publications

Defense by Volatiles in Leaf-Mining Insect Larvae

Defense by Volatiles in Leaf-Mining Insect Larvae

Synthesis and characterization of some oxidized derivatives of citronellal ethylene acetal

Chromenone Glucosides Acylated with Monoterpene Acids from the Leaves of Eucalyptus camaldulensis var. obtusa

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