Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
Angew Chem Int Ed Engl. 2017 Aug 1;56(32):9468-9472. doi: 10.1002/anie.201705333. Epub 2017 Jul 4.
Photo-mediated 6π cyclization is a valuable method for the formation of fused heterocyclic systems. Here we demonstrate that irradiation of cyclic 2-aryloxyketones with blue LED light in the presence of an Ir complex leads to efficient and high yielding arylation across a panoply of substrates by energy transfer. 2-Arylthioketones and 2-arylaminoketones also cyclize effectively under these conditions. Quantum calculation demonstrates that the reaction proceeds via conrotatory ring closure in the triplet excited state. Subsequent suprafacial 1,4-hydrogen shift and epimerization leads to the observed cis-fused products.
光介导的 6π 环化是形成稠合杂环体系的一种很有价值的方法。在这里，我们证明了在 Ir 配合物的存在下，用蓝色 LED 光照射环状 2-芳氧基酮，可以通过能量转移有效地进行各种底物的芳基化反应，产率很高。在这些条件下，2-芳硫代酮和 2-芳氨基酮也能有效地环化。量子计算表明，反应是通过三重态激发态的对旋环闭合进行的。随后的面外 1,4-氢迁移和差向异构化导致观察到的顺式稠合产物。
