Crossed acyloins were efficiently prepared by the thiazolium-catalysed condensation of two different unhindered aldehydes, using one mol equivalent of one aldehyde with three mol equivalents of the other. Conversion into the corresponding nonsymmetrical 1,2-dioxime was achieved either by oxidation with bismuth(III) oxide or the Dess−Martin periodinane to give a 1,2-diketone that was then treated with
Asymmetric total synthesis of humulane sesquiterpenoids alashanoids B, C, E, and F and 2,9-humuladien-6-ol-8-one
作者:Rasmita Barik、Samik Nanda
DOI:10.1039/d4ob00393d
日期:——
Naturally occurring sesquiterpenes having humulane frameworks are structurally intriguing and possess significant biological profiles. Asymmetric synthesis of the alashanoids B, C, E, and F and 2,9-humuladien-6-ol-8-one is achieved for the first time through a linear synthetic strategy. Intramolecular late-stage Nozaki–Hiyama–Kishi (NHK) coupling is employed to access the eleven-membered macrocyclic
具有葎草烷骨架的天然倍半萜在结构上很有趣并且具有重要的生物学特征。首次通过线性合成策略实现了阿拉素类化合物 B、C、E 和 F 以及 2,9-humuladien-6-ol-8-one 的不对称合成。采用分子内后期 Nozaki-Hiyama-Kishi (NHK) 偶联来访问目标分子中存在的十一元大环核心。使用埃文斯和非埃文斯顺式和反羟醛反应作为关键转化来获得 NHK 前体。 X 射线和 ECD 分析再次证实了合成化合物的结构和手性特性。