Department of Chemistry, Graduate School of Science, Osaka City University Sumiyoshi-ku, Osaka, 558-8585, Japan.
Faculty of Fisheries, Kagoshima University Shimoarata, Kagoshima, 8900056, Japan.
Chem Asian J. 2022 Jan 3;17(1):e202101137. doi: 10.1002/asia.202101137. Epub 2021 Nov 16.
There are marine cytotoxic bromotriterpenoids, named the thyrsiferol family that are structurally characterized by some tetrahydropyran (THP) and tetrahydrofuran (THF) rings. The thyrsiferol family belongs to natural products that are often difficult to determine their stereostructures even by the current, highly advanced spectroscopic methods, especially in acyclic systems including stereogenic tetrasubstituted carbon centers. In such cases, it is effective to predict and synthesize the possible stereostructures. Herein, to elucidate ambiguous stereostructures and unassigned absolute configurations of aplysiol B, laurenmariannol, and saiyacenol A, members of the thyrsiferol family, we carried out their asymmetric chemical syntheses featuring 6-exo and 5-exo oxacyclizations of epoxy alcohol precursors and 6-endo bromoetherification of a bishomoallylic alcohol. In this paper, we report total assignments of their stereostructures through their asymmetric chemical syntheses and also their preliminary cytotoxic activities against some tumor cells. These results could not have been achieved without depending on asymmetric total synthesis.
海洋细胞毒三萜类溴化物，被命名为 Thyrsiferol 家族，其结构特征为一些四氢吡喃（THP）和四氢呋喃（THF）环。Thyrsiferol 家族属于天然产物，即使使用当前高度先进的光谱方法，通常也很难确定其立体结构，尤其是在包括立体四取代碳原子中心的非环系统中。在这种情况下，预测和合成可能的立体结构是有效的。在这里，为了阐明 Thyrsiferol 家族成员 Aplysiol B、Laurenmariannol 和 Siyacenol A 的模糊立体结构和未分配的绝对构型，我们进行了它们的不对称化学合成，其特征在于环氧醇前体的 6-endo 和 5-exo 氧杂环化以及双烯丙基醇的 6-endo 溴醚化。在本文中，我们通过它们的不对称化学合成报告了它们的立体结构的全部分配，并报告了它们对一些肿瘤细胞的初步细胞毒性活性。如果没有依赖不对称全合成，就不可能取得这些结果。
