Wang Yi-Chi, Chen Cheng-Ru, Chen Chien-Yi, Liang Pi-Hui
School of Pharmacy, College of Medicine, National Taiwan University, Taipei 100, Taiwan.
J Org Chem. 2024 Apr 19;89(8):5491-5497. doi: 10.1021/acs.joc.3c02958. Epub 2024 Apr 10.
To meet the demand for quillaic acid, a multigram synthesis of quillaic acid was accomplished in 14 steps, starting from oleanolic acid, leading to an overall yield of 3.4%. Key features include C-H activation at C-16 and C-23. Through Pd-catalyzed C-H acetoxylation, the oxidation at C-23 was observed as the major product, as opposed to at C-24. A copper-mediated C-H hydroxylation using O successfully afforded the single isomer, 16β-ol triterpenoid, followed by configuration inversion to the desired 16α-ol compound. In summary, with steps optimized and conducted on a multigram scale, quillaic acid could be feasibly acquired through C-H activation with inexpensive copper catalysts, promoting a more sustainable approach.
为满足对齐墩果酸的需求,从齐墩果酸开始,经过14步反应完成了多克量级的齐墩果酸合成,总产率为3.4%。关键特征包括C-16和C-23处的C-H活化。通过钯催化的C-H乙酰氧基化反应,观察到C-23处的氧化产物是主要产物,而不是C-24处。使用O进行铜介导的C-H羟基化反应成功得到了单一异构体16β-醇三萜类化合物,随后构型翻转得到所需的16α-醇化合物。总之,通过优化步骤并在多克量级上进行,使用廉价的铜催化剂通过C-H活化可以可行地获得齐墩果酸,从而促进了一种更可持续的方法。