文献类型：期刊文献

英文题名：Intermolecular Photocyclizations of N-(omega-Hydroxyalkyl)-tetrachlorophthalimide with Alkenes Leading to Medium- and Large-Ring Heterocycles-Reaction Modes and Regio- and Stereoselectivity of the 1,n-Biradicals

作者：Shen, Yong-Miao[1,2];Yang, Xiao-Liang[1];Chen, Da-Qing[1];Xue, Jie[1];Zhu, Liang[1];Fun, Hoong-Kun[3];Hu, Hong-Wen[1];Xu, Jian-Hua[1]

机构：[1]Nanjing Univ, Inst Chem & Chem Engn, Nanjing 210093, Peoples R China;[2]Shaoxing Univ, Inst Chem & Chem Engn, Shaoxing 312000, Peoples R China;[3]Univ Sains Malaysia, Sch Phys, Xray Crystallog Unit, George Town 11800, Malaysia

年份：2010

卷号：16

期号：9

起止页码：2873

外文期刊名：CHEMISTRY-A EUROPEAN JOURNAL

收录：SCI-EXPANDED(收录号：WOS:000275943000029)、、WOS

基金：This work was supported by the National Natural Science Foundation of China (NSFC. 20572044). the International Scientific & Technological Exchange and Cooperation Foundation from the Ministry of Science and Technology of China (2007DFA41590). and the Zhejiang Provincial Natural Science Foundation (Y4080395).

语种：英文

外文关键词：biradicals; electron transfer; macrocycles medium-sized rings; stereoselectivity

外文摘要：A new photocyclization strategy by using intermolecular tandem reactions between N-(omega-hydroxyalkyl)4,5,6,7-tetrachlorophthalimides (1, 2, and 3) and a series of acyclic and cyclic alkenes is reported. Electron transfer of the triplet-excited phthalimide with the alkene and regioselective trapping of the alkene cation radical by the hydroxyl group at the phthalimide side chain gives a triplet 1,n-biradical, which after intersystem crossing (ISC) leads to regio- and diastereoselective synthesis of polycyclic heterocycles with an N,O-containing medium to large ring. Regio- and diastereoselectivity in the cyclizations are clarified by unambiguous steric structure assignments of the products by X-ray diffraction or extensive 2D NMR measurements. The diastereoselectivity is decided by the stereochemical course of the ISC process of the triplet 1,n-biradicals. These intermolecular photoreactions also furnish a new strategy to generate triplet 1,n-biradicals. Therefore, in photoreactions of I and 2 with phenylcyclollexene, the unprecedented stereoselective formation of products by intramolecular hydrogen-atom transfer in the 1,n-biradical intermediate was found (9 and 23). These facts provide direct verification to the reaction pathways of the 1,n-biradicals and give a new insight into the factors deciding reaction-pathway partitioning and stereoselectivity.