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  • epoxydiene  (2)
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  • 1
    ISSN: 1573-1561
    Keywords: Chiral HPLC ; sex pheromone ; Lepidoptera ; Geometridae ; epoxydiene ; stereochemistry ; Mosher's method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Resolution of insect pheromonal cis-epoxydiene racemates derived from (Z,Z,Z)-3,6,9-trienes with a C18–C23 chain was examined utilizing chiral HPLC columns, and the result showed that a Chiralpak AS column was suitable to separate enantiomers of the 3,4-epoxides, and a Chiralpak AD column was indispensable for the resolution of the racemic 6,7- and 9,10-epoxides. The absolute configuration of the enantiomers of the 3,4- and 9,10-epoxides separated by HPLC was studied after methanolysis of their epoxy rings. Examination of the 1H NMR data from esters of the methoxyalcohols produced by a modified Mosher's method with (S)- and (R)-α-methoxy-α-(trifluoromethyl)phenylacetic acid indicated that the dextrorotatory parent epoxides with a shorter R t were 3S,4R and 9S,10R isomers and the levorotatory enantiomers having a longer R t possessed 3R,4S and 9R,10S configuration. Field tests with both enantiomers of (Z,Z)-6,9-cis-3,4-epoxynonadecadiene separated by HPLC with the chiral column revealed new specific attraction of geometrid forest defoliators, Pachyerannis obliquaria, to the 3R,4S isomer and Zethenia albonotaria nesiotis to the 3S,4R isomer.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-1561
    Keywords: Chiral column ; reversed-phase HPLC ; resolution ; sex pheromone ; lepidopteran attractant ; stereochemistry ; epoxydiene ; mulberry looper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Resolution of insect pheromonal cis-epoxydiene racemates derived from (Z,Z,Z)-3,6,9-trienes was examined with a reversed-phase chiral HPLC column. The results showed that a Chiralcel OJ-R column was suitable for separating the enantiomers having a C17–C23 unsaturated straight chain except for 9,10-epoxydienes with a C21–C23 chain. To determine the absolute configuration of the separated enantiomers, each of the optically active epoxydienes was hydrogenated over Pd-BaSO4 and its behavior was examined on this chiral column by cochromatography with the corresponding chiral epoxy compound having a saturated chain, which was prepared via a Sharpless epoxidation reaction. This analysis showed that the dextrorotatory C17–C23 3,4- and 6,7-epoxydienes and C17–C20 9,10-epoxydienes with shorter R ts possess (3S,4R)-, (6S,7R)-, and (9R,10S) configurations, respectively, and the levorotatory enantiomers with longer R ts possess the opposite configuration. An abdominal tip extract of the mulberry looper, Hemerophila artilineata Butler (Lepidoptera: Geometridae: Ennominae), included (9S,10R)-(Z,Z)-cis-9,10-epoxy-3,6-octadecadiene as a main sex pheromone component. The synthetic (9S,10R)-9,10-epoxydiene, rather than its antipode, elicited strong antennal and behavioral responses from the male moths in electrophysiological and field tests.
    Type of Medium: Electronic Resource
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