Yu Peng, Zhang Wen, Lin Song
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.
Tetrahedron Lett. 2023 Jul 28;125. doi: 10.1016/j.tetlet.2023.154617. Epub 2023 Jun 22.
Radical cascade cyclization reactions provide an efficient method for the construction of polycyclic architectures with multiple stereogenic centers. However, achieving enantioselectivity control of this type of reaction is a challenging task. Here, we report an enantioselective cyclization of polyfunctional aryl cyclopropyl ketone and alkyne units, wherein the stereochemical outcome is directed by a chiral Ti(salen) catalyst. This transformation was proposed to proceed via a radical cascade process involving the reductive ring-opening of the cyclopropyl ketone followed by two annulation events entailing cyclization of the ensuing alkyl radical onto the alkyne and subsequent addition of the incipient vinyl radical to the Ti(IV)-enolate.
自由基串联环化反应为构建具有多个立体中心的多环结构提供了一种有效方法。然而，实现这类反应的对映选择性控制是一项具有挑战性的任务。在此，我们报道了多官能团芳基环丙基酮与炔烃单元的对映选择性环化反应，其中立体化学结果由手性Ti(salen)催化剂引导。该转化过程被认为是通过一个自由基串联过程进行的，该过程包括环丙基酮的还原开环，随后是两个环化事件，即随后的烷基自由基与炔烃环化，以及初始乙烯基自由基加成到Ti(IV)-烯醇化物上。
