« Previous AbstractTerahertz gas-phase spectroscopy: chemometrics for security and medical applications    Next AbstractReproductive division of labour and thelytoky result in sympatric barriers to gene flow in honeybees (Apis mellifera L.) »

Eur J Biochem

Title:		Stereochemical studies on algal pheromone biosynthesis. A model study with the flowering plant Senecio isatideus (Asteraceae)
Author(s):		Neumann C; Boland W;
Address:		"Institut fur Organische Chemie der Universitat, Karlsruhe, Federal Republic of Germany"
Journal Title:		Eur J Biochem
Year:		1990
Volume:		191
Issue:		2
Page Number:		453 - 459
DOI:		10.1111/j.1432-1033.1990.tb19143.x
ISSN/ISBN:		0014-2956 (Print) 0014-2956 (Linking)
Abstract:		"Unsaturated C8 and C11 hydrocarbons act as chemical signals (chemotaxis) during sexual reproduction of many marine brown algae. One of these compounds, namely (+)-(6S)-6-(1Z-butenyl)cyclohepta-1,4-diene (= ectocarpene) is also formed as a major hydrocarbon by the flowering plant Senecio isatideus (Asteraceae). On administration of enantiospecifically labelled (8R)- or (8S)-[7,8-2H2]trideca-3,6,9-trienoic acid instead of the natural precursor dodeca-3,6,9-trienoic acid to this plant, the artificial C12 analogue of ectocarpene is formed. Mass spectroscopic analysis of the metabolites revealed this process to be enantiospecific for the C(8)-HRe atom of the precursor acid. The stereochemical course of the overall reaction is in agreement with a precise, U-shaped embedding of the trienoic acid into the active center of the enzyme(s) and Re-attack onto a hydrogen at the C(8) methylene group of this precursor. The reactive intermediate cyclizes by pi-orbital interaction between C(4) and C(6) of the acid and is accompanied by decarboxylation. The first product is a thermally unstable (1S,2R)-cis-1-(1E,3Z-hexadienyl)-2-vinylcyclopropane, which immediately rearranges to (+)-(6S)-ectocarpene (homo-Cope rearrangement). The present work provides first experimental evidence for a homo-Cope rearrangement as a naturally occurring electrocyclic reaction"
Keywords:		"Cyclization Cycloheptanes/*metabolism Eukaryota/*metabolism Gas Chromatography-Mass Spectrometry Hot Temperature Models, Molecular Molecular Conformation Phaeophyta/*metabolism Pheromones/*metabolism Plants/*metabolism Stereoisomerism;"
Notes:		"MedlineNeumann, C Boland, W eng Comparative Study Research Support, Non-U.S. Gov't England 1990/07/31 Eur J Biochem. 1990 Jul 31; 191(2):453-9. doi: 10.1111/j.1432-1033.1990.tb19143.x"