Synthesis of Enantiomerically Enriched 2,5-Dihydrofuran Derivatives from Easily Available Enantiomerically Enriched 2-Butyne-1,4-diols by Stereospecific Transformation
作者:Hiroyuki Saimoto、Masaru Yasui、Shin-ichiro Ohrai、Hiroshige Oikawa、Kazuhiro Yokoyama、Yoshihiro Shigemasa
DOI:10.1246/bcsj.72.279
日期:1999.2
The transformation of enantiomerically enriched 1,1,4-trisubstituted 4-acyloxy-2-butyn-1-ols 3 into 2,2,5-trisubstituted 3-acyloxy-2,5-dihydrofurans 5 with complete stereospecificity was achieved by an Ag(I)-mediated rearrangement of the monoesters 3 to allenic intermediates 4, followed by Ag(I)-assisted cyclization. A stereochemical analysis revealed that the newly formed carbon–oxygen bond in 5 was
对映体富集的 1,1,4-三取代 4-acyloxy-2-butyn-1-ols 3 转化为具有完全立体定向性的 2,2,5-三取代 3-acyloxy-2,5-dihydrofurans 5 是通过 Ag 实现的(I) 介导的单酯 3 重排为丙二烯中间体 4,然后是 Ag(I) 辅助的环化。立体化学分析表明,5 中新形成的碳氧键是从 3 中裂解的碳氧键的背面形成的。炔丙酯 3 是通过对映选择性还原相应的炔基酮 1,然后进行酰化而制备的. 由于 3-acyloxy-2,5-dihydrofurans 5 很容易转化为相应的 4,5-dihydro-3(2H)-furanones 6,因此该序列成功应用于合成诱导分化的抗生素 (S)- (-)-ascofuranone。