Cao Li-Ya, Luo Jian-Nan, Yao Jia-Sheng, Wang De-Ku, Dong Yuan-Qing, Zheng Chao, Zhuo Chun-Xiang
State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province, and, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, P. R. China.
Angew Chem Int Ed Engl. 2021 Jul 5;60(28):15254-15259. doi: 10.1002/anie.202103429. Epub 2021 Jun 4.
The transition-metal-catalyzed cyclopropanation of alkenes by the decomposition of diazo compounds is a powerful and straightforward strategy to produce cyclopropanes, but is tempered by the potentially explosive nature of diazo substrates. Herein we report the Mo-catalyzed regiospecific deoxygenative cyclopropanation of readily available and bench-stable 1,2-dicarbonyl compounds, in which one of the two carbonyl groups acts as a carbene equivalent upon deoxygenation and engages in the subsequent cyclopropanation process. The use of a commercially available Mo catalyst afforded an array of valuable cyclopropanes with exclusive regioselectivity in up to 90 % yield. The synthetic utility of this method was further demonstrated by gram-scale syntheses, late-stage functionalization, and the cyclopropanation of a simple monocarbonyl compound. Preliminary mechanistic studies suggest that phosphine (or silane) acts as both a mild reductant and a good oxygen acceptor that efficiently regenerates the catalytically active Mo catalyst through reduction of the Mo-oxo complexes.
通过重氮化合物分解实现的过渡金属催化的烯烃环丙烷化反应是一种强大且直接的制备环丙烷的策略，但重氮底物潜在的爆炸性限制了该反应的应用。在此，我们报道了钼催化的、区域选择性的脱氧环丙烷化反应，该反应以易于获得且在实验室条件下稳定的1,2 - 二羰基化合物为原料，其中两个羰基之一在脱氧后作为卡宾等价物参与后续的环丙烷化过程。使用市售的钼催化剂能够以高达90%的产率、专一的区域选择性得到一系列有价值的环丙烷。克级规模合成、后期官能团化以及简单单羰基化合物的环丙烷化反应进一步证明了该方法的合成实用性。初步机理研究表明，膦（或硅烷）既是温和的还原剂，又是良好的氧受体，通过还原钼氧配合物能有效地再生具有催化活性的钼催化剂。
