Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , Lichtenbergstrasse 4 , 85747 Garching , Germany.
J Org Chem. 2018 Mar 16;83(6):3069-3077. doi: 10.1021/acs.joc.8b00238. Epub 2018 Mar 6.
The arene ring of the title compounds is cleaved by a reaction cascade which is initiated by an intramolecular ortho photocycloaddition reaction. Tricyclic products were obtained in a highly regio- and diastereoselective fashion via a cyclooctatriene intermediate. The facial diastereoselectivity exerted by a stereogenic center in the tether is moderate to good (dr = 65/35 to 82/18). Yields were acceptable (44-87%) except for a single substrate which had a geminal dimethyl substitution in the tether and which gave the respective product in only 14% yield. The reaction is stereoconvergent with regard to the olefin configuration ( E or Z) in agreement with a triplet mechanism of the ortho photocycloaddition step.
标题化合物的芳环通过反应级联断裂，该反应级联由分子内邻位光环加成反应引发。通过环辛三烯中间体以高区域和立体选择性的方式获得三环产物。由连接体中的手性中心施加的面选择性立体异构体适中到良好（dr = 65/35 至 82/18）。除了一个带有连接体中偕二甲基取代基的单个底物外，产率可以接受（44-87%），该底物仅以 14%的产率得到相应产物。该反应在烯烃构型（E 或 Z）方面是立体协同的，与邻位光环加成步骤的三重态机制一致。
