title: Absolute configuration of 7-epi-sesquithujene.
abstract: 7-epi-sesquithujene (1) is a bicyclic sesquiterpene isolated from phoebe oil, an essential oil of the Brazilian walnut tree, Phoebe porosa. It is also produced by stressed ash trees and has been shown to elicit strong electrophysiological responses on emerald ash borer, Agrilus planipennis, antennae. In the course of the development of a synthetic 7-epi-sesquithujene lure for field testing against the emerald ash borer, we found that the absolute configuration of this compound had not been determined. We isolated >95% pure 7-epi-sesquithujene from phoebe oil via successive fractionation and conventional and argentation (HPLC) chromatographies. The specific optical rotation of this compound matched that of a synthetic product of known configuration. We also synthesized two other stereoisomers of sesquithujene and developed a chiral GC method to separate all four. Based on the specific rotation, stereoselective syntheses, and chiral GC analyses, 7-epi-sesquithujene present in phoebe oil and white ash was found to have the 2S,6S,7R absolute configuration.
authors.affiliation: Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, Bldg. 007, Rm. 326, BARC-West, 10300 Baltimore Avenue, Beltsville, Maryland 20705, USA. khrimian@ars.usda.gov
authors.forename: Ashot
authors.initials: A
authors.lastname: Khrimian
authors.forename: Allard A
authors.initials: AA
authors.lastname: Cossé
authors.forename: Damon J
authors.initials: DJ
authors.lastname: Crook
mesh_terms: D000818:Animals; D001938:Brazil; D001517:Coleoptera / Q000502:physiology*; D031661:Fraxinus; D019770:Lauraceae / Q000737:chemistry* / Q000235:genetics; D015394:Molecular Structure; D000081222:Monocyclic Sesquiterpenes; D009822:Oils, Volatile / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry; D012717:Sesquiterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: C561437:7-epi-sesquithujene; D000081222:Monocyclic Sesquiterpenes; D009822:Oils, Volatile; D010938:Plant Oils; D012717:Sesquiterpenes