Highly Efficient and Tunable Synthesis of Dioxabicyclo[4.2.1] Ketals and Tetrahydropyrans via Gold-Catalyzed Cycloisomerization of 2-Alkynyl-1,5-diols
作者:Le-Ping Liu、Gerald B. Hammond
DOI:10.1021/ol902215n
日期:2009.11.5
A highly efficient gold(I) chloride catalyzed cycloisomerization of 2-alkynyl-1,5-diol (1) to dioxabicyclo[4.2.1] ketal (2) and its further transformation to tetrahydropyran (3) are reported. The diol is readily obtained by the reduction of 2-alkynyl-substituted glutarates, isolated from the Michael addition of allenoates to methyl acrylate. These reactions proceeded smoothly under very mild conditions
报道了一种高效的金(I)氯化金催化的2-炔基-1,5-二醇(1)向二氧杂双环[4.2.1]缩酮(2)的环异构化及其进一步转化为四氢吡喃(3)。二醇可通过还原2-炔基取代的戊二酸酯而容易地获得,所述2-炔基取代的戊二酸酯是从烯丙酸酯的迈克尔加成到丙烯酸甲酯中分离的。这些反应在非常温和的条件下顺利进行。提出了从相应的缩酮形成所述四氢吡喃的合理机理。