Sauvé Ethan R, Mayder Don M, Kamal Saeid, Oderinde Martins S, Hudson Zachary M
Department of Chemistry, The University of British Columbia 2036 Main Mall, Vancouver British Columbia V6T 1Z1 Canada
Department of Discovery Synthesis, Bristol Myers Squibb Research and Early Development 3551 Lawrenceville Road, Princeton New Jersey 08540 USA
Chem Sci. 2022 Jan 27;13(8):2296-2302. doi: 10.1039/d1sc05098b. eCollection 2022 Feb 23.
Energy transfer (EnT) is a fundamental activation process in visible-light-promoted photocycloaddition reactions. This work describes the performance of imidazoacridine-based TADF materials for visible-light mediated triplet-triplet EnT photocatalysis. The TADF material ACR-IMAC has been discovered as an inexpensive, high-performance organic alternative to the commonly used metal-based photosensitizers for visible-light EnT photocatalysis. The efficiency of ACR-IMAC as a photosensitizer is comparable with Ir-based photosensitizers in both intra- and intermolecular [2 + 2] cycloadditions. ACR-IMAC mediated both dearomative and non-dearomative [2 + 2] cycloadditions in good yields, with high regio- and diastereocontrol. Cyclobutane-containing bi- tri- and tetracylic scaffolds were successfully prepared, with broad tolerance toward functional groups relevant to drug discovery campaigns. Fluorescence quenching experiments, time-correlated single-photon counting, and transient absorption spectroscopy were also conducted to provide insight into the reaction and evidence for an EnT mechanism.
能量转移（EnT）是可见光促进的光环加成反应中的一个基本活化过程。这项工作描述了基于咪唑并吖啶的热活化延迟荧光（TADF）材料在可见光介导的三重态-三重态能量转移光催化中的性能。已发现TADF材料ACR-IMAC是一种廉价、高性能的有机材料，可替代常用于可见光能量转移光催化的金属基光敏剂。在分子内和分子间的[2 + 2]环加成反应中，ACR-IMAC作为光敏剂的效率与基于铱的光敏剂相当。ACR-IMAC介导的去芳构化和非去芳构化[2 + 2]环加成反应均具有良好的产率，具有高区域和非对映选择性控制。成功制备了含环丁烷的双环、三环和四环支架，对与药物发现活动相关的官能团具有广泛的耐受性。还进行了荧光猝灭实验、时间相关单光子计数和瞬态吸收光谱，以深入了解反应并为能量转移机制提供证据。
