Stereoselective total synthesis of clonostachydiol
摘要:
A simple and efficient stereoselective synthesis of clonostachydiol was achieved using ethyl (R)-3-hydroxybutanoate 5 and methyl (R)-2-hydroxypropanoate 12 as readily available starting materials. The key steps involved in the synthesis were MacMillan alpha-hydroxylation, Horner-Wadsworth-Emmons (HWE) olefination, a Grignard reaction, and Hoveyda-Grubbs IInd generation catalyzed ring closing metathesis (RCM). (C) 2012 Elsevier Ltd. All rights reserved.
An enantioselective totalsynthesis of the natural product (−)-preussochromone A is reported. The tricyclic thiopyrane skeleton could be assembled via Lewis acid-mediated cycloisomerization of a precursor with a 2-thiochromenone substructure and an α-ketoester moiety. The chromenone core was synthesized by cyclization of a dithioketene acetal and oxidation to a 2-sulfonylchromenone to set up the subsequent
报道了天然产物 (-)-preussochromone A 的对映选择性全合成。三环噻喃骨架可以通过路易斯酸介导的前体环异构化组装,该前体具有 2-硫代色酮亚结构和 α-酮酯部分。色烯酮核心是通过二硫酮缩醛环化和氧化成 2-磺酰基色烯酮来合成的,以建立脂肪族硫醇的后续硫杂-迈克尔-逆-迈克尔加成,产生高度氧化的侧链。