CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry , Central China Normal University , 152 Luoyu Road , Wuhan 430079 , China.
School of Chemistry and Chemical Engineering , Chongqing University , Chongqing 400030 , China.
J Am Chem Soc. 2019 Jan 9;141(1):133-137. doi: 10.1021/jacs.8b12095. Epub 2018 Dec 17.
An enantioselective [5+2] cycloaddition of vinylethylene carbonates and α-diazoketones was achieved for the first time by merging photoactivation and asymmetric Pd catalysis. The key to the success of this method is the enantioselective trapping of Pd-containing, 1,5-dipolar intermediates by ketenes, a class of reactive C2 synthons, which were generated in an in situ and traceless manner under visible light irradiation. Through this trapping, a variety of 7-membered lactones bearing challenging chiral quaternary stereocenters can be accessed in a facile manner with good efficiency and high enantioselectivity (up to 99% yield and 96:4 er).
首次通过光活化和不对称钯催化相结合，实现了乙烯基碳酸酯和α-重氮酮的对映选择性[5+2]环加成反应。该方法的关键在于通过碳烯，一种反应性 C2 合成子，对含钯的 1,5-二极中间体进行对映选择性捕获，碳烯在可见光照射下以原位和无痕迹的方式生成。通过这种捕获，可以以简便的方式获得多种具有挑战性的手性季碳中心的 7 元内酯，产率高（高达 99%），对映选择性好（高达 96:4 er）。
