Department Chemie und Catalysis Research Center, CRC, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany.
Angew Chem Int Ed Engl. 2018 Jan 15;57(3):827-831. doi: 10.1002/anie.201710441. Epub 2017 Dec 13.
Εniminium ions were prepared from the corresponding α,β-unsaturated carbonyl compounds (enones and enals), and were found to be promoted to their respective triplet states by energy transfer. The photoexcited intermediates underwent intra- or intermolecular [2+2] photocycloaddition in good yields (50-78 %) upon irradiation at λ=433 nm or λ=457 nm. Iridium or ruthenium complexes with a sufficiently high triplet energy were identified as efficient catalysts (2.5 mol % catalyst loading) for the reaction. The intermolecular [2+2] photocycloaddition of an eniminium ion derived from a chiral secondary amine proceeded with high enantioselectivity (88 % ee).
从相应的α,β-不饱和羰基化合物（烯酮和烯醛）制备了 Eniminium 离子，并发现它们通过能量转移被促进到各自的三重态。在 433nm 或 457nm 照射下，光激发中间体经历了良好收率（50-78%）的分子内或分子间[2+2]光环加成反应。具有足够高三重态能量的铱或钌配合物被确定为该反应的有效催化剂（2.5mol%催化剂负载量）。衍生自手性仲胺的 Eniminium 离子的分子间[2+2]光环加成反应具有高对映选择性（88%ee）。
