- Beetles Do It Differently: Two Stereodivergent Cyclisation Modes in Iridoid-Producing Leaf-Beetle Larvae
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Larvae of the Chrysomelina species Phaedon cochleariae, Hydrothassa marginella, Phratora vulgatissima, Gastrophysa viridula, Gastrophysa atrocyanea, Gastrophysa cyanea and Gastrophysa polygoni produce the iridoid chrysomelidial (1) to defend themselves against predators. Feeding experiments with a deuterated precursor ([2H5]8-hydroxygeraniol 9) and in vitro isotope exchange experiments with defensive secretion in 2H2O revealed differences in the cyclisation of the ultimate precursor 8-oxogeranial (8) to 1, between members of the genus Gastrophysa and all other species. In P. cochleariae, H. marginella and P. vulgatissima 1 is most likely produced by a Rauhut-Currier-type cyclisation via a transoid dienamine , with loss of a single deuterium atom from C(4) of the precursor. In contrast, members of the genus Gastrophysa cyclise 8 via a cisoid dienamine intermediate, with exchange of all three deuterium atoms from the methyl group at C(3). To study whether the different cyclisation modes influence the stereochemistry of 1, the absolute configuration of 1 of the larvae was determined by GC-MS on a chiral column. In accordance with literature (J. Meinwald, T. H. Jones, J. Am. Chem. Soc. 1978, 100, 1883 and N. Shimizu, R. Yakumaru, T. Sakata, S. Shimano, Y. Kuwahara, J. Chem. Ecol. 2012, 38, 29), we found (5S,8S)-chrysomelidial (1) in H. marginella and P. vulgatissima, but P. cochleariae and all investigated members of the genus Gastrophysa synthesise (5R,8R)-chrysomelidial (1).
- Kunert, Maritta,Rahfeld, Peter,Shaker, Kamel H.,Schneider, Bernd,David, Anja,Dettner, Konrad,Pasteels, Jacques M.,Boland, Wilhelm
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- CHRYSOMELIDIAL BY CHROMYL CHLORIDE OXIDATION: A REVISED STRUCTURE FOR GASTROLACTONE
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Non-conjugated gem-dialkylated alkenes were oxidized to aldehydes in the presence of α,β-unsaturated carbonyl functional groups, providing a new synthesis of 1 and a synthesis of 2 that led to a revised structure for gastrolactone.
- Jones, Tappey H.,Blum, Murray S.,Fales, H. M.
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- THE BASE-CATALYZED CYCLIZATION OF 10-OXOCITRAL. SYNTHESIS OF CHRYSOMELIDIAL AND DEHYDROIRIDODIAL
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Base treatment of 10-oxocitral (1) gives chrysomelidial (9) and dehydroiridodial (10), supporting the intermediacy of 1 in the biosynthesis of some iridoid glucosides.Cannizzaro reaction of 9 and 10 affords regioselectively a new iridolactone, 1,2-dehydroisoiridomirmecin (13).
- Bellesia, Franco,Ghelfi, Franco,Pagnoni, Ugo M.,Pinetti, Adriano
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p. 381 - 382
(2007/10/02)
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- FUNCTIONALIZED CYCLOPENTANE DERIVATIVES FROM THE PHOTOADDUCTS OF METHYL 2,4-DIOXOPENTANOATE-OLEFINS: ALTERNATIVE SYNTHESES OF dl-DEHYDROIRIDODIAL AND dl-CHRYSOMELIDIAL
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Functionalized cyclopentane derivatives were prepared by the retro-ozonolysis of methyl 2,6-dioxoheptanoates, which are readily accessible from the photocycloaddition of methyl 2,4-dioxopentanoate with olefins.By this method, 3-isopropenyl-2-methoxycarbonyl-1-methylcyclopentene, a versatile intermediate to iridoid terpenoids, and 1-methoxycarbonyl-2,6,6-trimethylfulvene were synthesized from isoprene.Alternative syntheses of dl-dehydroiridodial and dl-chrysomelidial were accomplished.
- Takeshita, Hitoshi,Hatsui, Toshihide,Kato, Nobuo,Masuda, Takeshi,Tagoshi, Hirotaka
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p. 1153 - 1156
(2007/10/02)
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- TRICYCLO2,8>OCTANONES AS BUILDING BLOCKS IN NATURAL PRODUCTS SYNTHESIS (I). --THE SYNTHESIS OF CHRYSOMELIDIAL--
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The stereocontrolled synthesis of chrysomelidial from 4-methyl-tricyclo2,8>octan-3-one is described.
- Kon, Kenji,Isoe, Sachihiko
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p. 3399 - 3402
(2007/10/02)
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