Absolute Configuration of 7-<i>epi</i>-Sesquithujene
作者:Ashot Khrimian、Allard A. Cossé、Damon J. Crook
DOI:10.1021/np200098z
日期:2011.6.24
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.
A Gold-Catalyzed Entry into the Sesquisabinene and Sesquithujene Families of Terpenoids and Formal Total Syntheses of Cedrene and Cedrol
作者:Alois Fürstner、Andreas Schlecker
DOI:10.1002/chem.200801382
日期:2008.10.20
into the bicyclic cyclopropyl ketone derivatives 5 and 6 by way of a gold-catalyzed Ohloff-Rautenstrauch-type enynecycloisomerization is described. The required substrates were prepared by an asymmetric addition of the branched allylzinc reagent 21 to the alkynyl aldehyde 17 mediated by the deprotonated bisoxazoline (BOX) ligand 22. Compounds 5 and 6 were then converted into a host of different members