Norbisabolane and bisabolane sesquiterpenoids from the seeds of Angelica keiskei
作者:Shinji Ohta、Yasunori Yuasa、Nobuwa Aoki、Emi Ohta、Tatsuo Nehira、Hisashi Ômura、Mylene M. Uy
DOI:10.1016/j.phytol.2019.08.006
日期:2019.10
norbisabolane-type sesquiterpenoid, ashitabaol B and two bisabolane-type sesquiterpenoids, ashitabaols C and D, were isolated together with known sesquiterpenoids, ashitabaol A and (+)-bisabolangelone, from the seeds of Angelica keiskei (Miq.) Koidz. The structures including absolute configuration were determined on the basis of their spectroscopy, X-ray crystallography, and chemical conversions.
The absoluteconfiguration of bisabolangelone has been established by an eleven step total synthesis of the corresponding TMS protected antipode starting from (R)-(+)-pulegone. Comparison of the TMS-derivatives by GC on a chiral column, allowed us to assign the absoluteconfiguration of the synthetic compound and thus of the corresponding natural product. The latter has been confirmed by the Mosher's
Bisabolangelone is a sesquiterpenoid well known for its strong antifeeding properties against phytophagous insects. In this communication, we describe the total synthesis of the target molecule, following a model study, wich shows the possibilities to cyclizise γ-acetylenic alcohols, in view to obtain 2-(2-alkenylidene)-tetrahydrofurans, an essential moiety of bisabolangelone.