University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute for Organic Chemistry, Greinstr. 4-6, Köln D-50939, Germany.
University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute for Inorganic Chemistry, Greinstr. 4-6, Köln D-50939, Germany.
Chem Commun (Camb). 2022 Nov 22;58(93):12999-13002. doi: 10.1039/d2cc04693h.
Photocatalytic [2+2]-cycloadditions between cyclic enones and electron-rich cyclic enol ethers are initiated by triplet-triplet energy transfer from an excited iridium photocatalyst to the enone acceptor. The composition of the resulting cycloadduct mixture shows a surprising time dependency of the cyclobutane stereoisomeric ratio which indicates that the products are not photostable under the reaction conditions. The isomerisation of the cycloadducts 3 by a photoinduced redox process points to a switch from triplet energy transfer (PenT) to photoinduced electron transfer (PET) catalysis.
光催化[2+2]-环加成反应是在三重态-三重态能量转移的作用下发生的，反应中环状烯酮和富电子环状烯醇醚作为电子给体和受体。所得环加成混合物的组成表现出令人惊讶的顺式-反式环丁烷立体异构体比例的时间依赖性，这表明在反应条件下产物不稳定。光诱导氧化还原过程导致环加成物 3 的异构化，表明从三重态能量转移（PenT）到光诱导电子转移（PET）催化的转变。
