5. The stereoselective installation of methyl group at C-3 by using LiHMDS and MeI completed the synthesis of racemic eupomatilone-6 (2) and its diastereomer 3. The spectroscopic data of 2 was in full agreement with reported spectra of natural product, thus confirming the revised relative configuration of eupomatilone-6. Similarly, an optically active (3R,4R,5S)-isomer of eupomatilone-6 (23) was prepared
Zn介导的联芳基醛8与
巴豆基
溴的Barbier反应,然后进行
硼氢化和氧化,得到
γ-丁内酯4和5。利用Li
HMDS和MeI在C-3处进行立体选择性的甲基安装,完成了外消旋的eupomatilone-6(2)及其非对映体3的合成。的光谱数据2是与
天然产物的报道光谱完全一致,从而证实eupomatilone-6的修订相对构型。类似地,依托匹美酮6的旋光(3 R,4 R,5 S)异构体(23制备),其中以
噻唑烷
硫酮为手性助剂的醛醇缩合反应为关键步骤。基于23的光谱数据和旋光度值,提出了eupomatilone-6的绝对构型。