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.
J Nat Prod. 2011 Jun 24;74(6):1414-20. doi: 10.1021/np200098z. Epub 2011 May 16.
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.
7-epi-表愈创木烯（1）是一种从巴西胡桃木油（巴西胡桃木的一种精油）中分离出来的双环倍半萜烯。它也由受压的白蜡树产生，并已被证明对翡翠灰象鼻虫 Agrilus planipennis 的触角有强烈的电生理反应。在为野外测试针对翡翠灰象鼻虫而合成的 7-epi-表愈创木烯诱饵的过程中，我们发现该化合物的绝对构型尚未确定。我们通过连续的分馏以及常规和银（HPLC）层析法从 Phoebe 油中分离出>95%纯度的 7-epi-表愈创木烯。该化合物的比旋光度与已知构型的合成产物相匹配。我们还合成了愈创木烯的另外两种立体异构体，并开发了一种手性 GC 方法来分离这四种化合物。根据比旋光度、立体选择性合成和手性 GC 分析，从 Phoebe 油和白蜡中分离出的 7-epi-表愈创木烯具有 2S,6S,7R 的绝对构型。
