of tert-butyl ynoates afforded α-pyrone cores of violapyrones. Moreover, this reaction was successfully applied to the stereospecific syntheses of (+)- and (–)-violapyrone C, which allowed the absolute configuration of natural (+)-violapyrone C to be assigned by comparison of the optical rotations. This first total synthesis, which proceeded in 22 % yield over 10 steps from (S)-(–)-2-methylbutanol, features
金 (I) 催化的 ynoates 叔丁酯的分子内 6-endo-dig 环化得到 violapyrones 的 α-pyrone 核。此外,该反应成功地应用于 (+)- 和 (-)-violapyrone C 的立体有择合成,这允许通过比较旋光度来分配天然 (+)-violapyrone C 的绝对构型。这是第一次全合成,从 (S)-(-)-
2-甲基丁醇以 22% 的产率进行 10 个步骤,具有
氧化银 (I) 促进
1,4-丁二醇的单苄基化、Wittig 烯化、克莱森缩合、Corey– Fuchs 反应和
金 (I) 催化的
α-吡喃酮合成。