Total Synthesis of Enantiopure Pyrrhoxanthin: Alternative Methods for the Stereoselective Preparation of 4-Alkylidenebutenolides
作者:Belén Vaz、Leticia Otero、Rosana Álvarez、Ángel R. de Lera
DOI:10.1002/chem.201301873
日期:2013.9.23
A new stereocontrolled total synthesis of the configurationally labile C37‐norcarotenoid pyrrhoxanthin in enantiopure form has been completed. A highly stereoselective Horner–Wadsworth–Emmons (HWE) condensation of a C17‐allylphosphonate and a C20‐aldehyde was used as the last conjunctive step. Both a Sonogashira reaction to form the C17‐phosphonate and the final HWE condensation proved to be compatible
对映纯形式的结构不稳定的C 37-去类胡萝卜素黄嘌呤的新的立体控制的全合成已完成。最后一个结合步骤使用了C 17烯丙基膦酸酯和C 20醛的高度立体选择性Horner-Wadsworth-Emmons(HWE)缩合反应。Sonogashira反应形成C 17-膦酸酯的反应和最终的HWE缩合都证明与敏感的C7–C10烯炔E构型兼容。三种选择性的戊2烯4烯4炔酸前体的区域选择性(5 exo dig)银促进的内酯化反应,包括增加的复杂功能的C 20对碎片进行了研究,以制备γ-亚烷基丁烯内酯片段。这项调查扩展了制备含氧类胡萝卜素(叶黄素)的现有方法,并简化了天然产物C 37-类胡萝卜素丁烯内酯家族的其他成员的合成。