Enantioselective Synthesis of (−)-Terpestacin and Structural Revision of Siccanol Using Catalytic Stereoselective Fragment Couplings and Macrocyclizations
作者:Johann Chan、Timothy F. Jamison
DOI:10.1021/ja0470968
日期:2004.9.1
(-)-Terpestacin (1, naturally occurring enantiomer) and (+)-11-epi-terpestacin (2) were prepared using catalyst-controlled, stereoselective, intermolecular reductive coupling reactions of alkyne 9 and aldehyde 10, affording allylic alcohols 42 or 11-epi-42 in a 3:1 ratio (or 1:3 depending on the enantiomer of ligand 41a used). These stereoselective fragment couplings were instrumental in confirming that "siccanol" is not 11-epi-terpestacin but, in fact, is (-)-terpestacin itself. Several intramolecular alkyne-aldehyde reductive coupling approaches to 1 and 2 were also investigated and are discussed herein.
(-)-Terpestacin(1,天然存在的对映体)和 (+)-11-epi-terpestacin(2)是通过催化剂控制的、具有立体选择性的分子间还原偶联反应制备的。具体来说,使用炔烃 9 和醛 10 进行反应,以 3:1 的比例(或根据配体 41a 的对映体不同而为 1:3)生成 allylic 酒精 42 或 11-epi-42。这些具有立体选择性的片段偶联反应对于确认“siccanol”不是 11-epi-terpestacin 至关重要,而是实际上为 (-)-terpestacin 本身。此外,文中还探讨了多种分子内炔烃-醛还原偶联方法来制备 1 和 2。