Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Org Lett. 2023 Feb 10;25(5):889-894. doi: 10.1021/acs.orglett.3c00131. Epub 2023 Feb 1.
In metal hydride-catalyzed alkene hydrofunctionalization reactions via hydrogen atom transfer, simple carbonyl groups have been well-recognized as good somophiles at the carbon for C-C bond formation. Here we report an alternative pathway exploring the carbonyl as an O-nucleophile to make new C-O bonds during the CoH-catalyzed oxidative cyclization of alkenyl aldehydes. This reaction provides a rapid, mild, modular, and stereoselective (up to >20:1) entry to saturated O-heterocycles via nucleophilic trapping of an in situ-formed oxocarbenium intermediate. The key to overriding the carbonyl's innate somophilicity was found to be promoting the formation of organocobalt species and suppressing the radical exchange.
在通过氢原子转移的金属氢化物催化烯烃氢官能化反应中，简单的羰基被公认为在碳上形成 C-C 键的良好亲核体。在这里，我们报告了一种替代途径，即在 CoH 催化的烯基醛的氧化环化过程中，探索羰基作为 O-亲核试剂形成新的 C-O 键。该反应通过原位形成的氧杂碳正离子中间体的亲核捕获，提供了一种快速、温和、模块化和立体选择性（高达>20:1）的方法，进入饱和的 O-杂环。发现克服羰基固有亲核性的关键是促进有机钴物种的形成和抑制自由基交换。
