Department of Chemistry, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
Org Lett. 2017 Oct 6;19(19):5268-5271. doi: 10.1021/acs.orglett.7b02537. Epub 2017 Sep 11.
The first example of a regioselective and enantioselective intermolecular Buchner ring expansion is reported using continuous flow. The practicality and scope of the reaction are greatly improved under flow conditions. Reactions of ethyl diazoacetate with symmetric and nonsymmetric arenes afford cycloheptatrienes in good yield and excellent regioselectivity. The first example of an asymmetric intermolecular Buchner reaction is demonstrated with disubstituted diazo esters in good to excellent enantioselectivity. The asymmetric reactions proceed with absolute regioselectivity to afford cycloheptatrienes with an all-carbon quaternary center.
本文报道了首例使用连续流技术实现区域和对映选择性的 Buchner 环扩张反应。在流动条件下，反应的实用性和范围得到了极大的改善。重氮乙酸乙酯与对称和非对称芳烃的反应以良好的收率和优异的区域选择性得到环庚三烯。首例不对称分子间 Buchner 反应是用取代的重氮酯以良好到优秀的对映选择性得到的。不对称反应具有绝对区域选择性，以全碳季碳中心的形式得到环庚三烯。
