Chai Hongli, Wang Xueqing, Ma Xingyu, Zhen Xiang, Qin Yuji, Qi Liang, Xu Zhaoqing, Li Fuchong, Zhu Weiwei
School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China.
Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Science, Lanzhou University, Lanzhou 730000, China.
Org Lett. 2024 Mar 8;26(9):1775-1779. doi: 10.1021/acs.orglett.3c04172. Epub 2024 Feb 26.
Herein, BF·EtO-promoted O-insertion/spirocyclization/fluorination/ring-expansion of unsaturated amides to synthesis of spiro[benzo[b]-[1,4]dioxepine-3,5'-oxazole] skeletons in the presence of natural light and O (Σ) was reported. Air was the oxygen source of the O-generation and O-insertion reaction under metal-free and mild conditions. BF·EtO played multiple roles, such as Lewis acid, activating reagent, and fluorine source in the reported cascade. A mechanism involving O generation/activation of double bond/O-insertion/spirocyclization/fluorination/ring expansion was supposed.
在此，报道了在自然光和O(Σ)存在下，BF·EtO促进不饱和酰胺的O-插入/螺环化/氟化/扩环反应，以合成螺[苯并[b]-[1,4]二氧杂环庚烷-3,5'-恶唑]骨架。空气是无金属温和条件下O生成和O-插入反应的氧源。在报道的串联反应中，BF·EtO起到多种作用，如路易斯酸、活化试剂和氟源。推测了一个涉及O生成/双键活化/O-插入/螺环化/氟化/扩环的机理。
