Sandvoß Alexander, Maag Henning, Daniliuc Constantin G, Schollmeyer Dieter, Wahl Johannes M
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Corrensstraße 36 48149 Münster Germany.
Department Chemie, Johannes Gutenberg-Universität Duesbergweg 10-14 55128 Mainz Germany
Chem Sci. 2022 May 4;13(21):6297-6302. doi: 10.1039/d2sc01547a. eCollection 2022 Jun 1.
Identification of an electron poor trifluoroacetophenone allows the formation of uniquely stable hemiketals from prochiral oxetanols. When exposed to a cobalt(ii) catalyst, efficient ring-opening to densely functionalized dioxolanes is observed. Mechanistic studies suggest an unprecedented redox process between the cobalt(ii) catalyst and the hemiketal that initiates the oxetane-opening. Based on this observation, a dynamic kinetic resolution of the transient hemiketals is explored that uses a Katsuki-type ligand for stereoinduction (up to 99 : 1 dr and 96 : 4 er) and allows a variety of 1,3-dioxolanes to be accessed (20 examples up to 98% yield).
贫电子三氟苯乙酮的识别使得从手性氧杂环丁醇形成独特稳定的半缩酮成为可能。当暴露于钴（II）催化剂时，可观察到其高效开环生成功能密集的二氧戊环。机理研究表明，钴（II）催化剂与半缩酮之间存在前所未有的氧化还原过程，该过程引发了氧杂环丁烷的开环。基于这一观察结果，探索了瞬态半缩酮的动态动力学拆分，该拆分使用 Katsuki 型配体进行立体诱导（高达 99:1 的非对映体比例和 96:4 的对映体比例），并可获得多种 1,3 - 二氧戊环（20 个实例，产率高达 98%）。
