Shon Jong-Hwa, Kim Dooyoung, Rathnayake Manjula D, Sittel Steven, Weaver Jimmie, Teets Thomas S
Department of Chemistry, University of Houston 3585 Cullen Blvd., Room 112 Houston TX 77204-5003 USA
Department of Chemistry, Oklahoma State University 107, Physical Science Stillwater OK 74078 USA.
Chem Sci. 2021 Jan 29;12(11):4069-4078. doi: 10.1039/d0sc06306a.
Photoredox catalysis has emerged as a powerful strategy in synthetic organic chemistry, but substrates that are difficult to reduce either require complex reaction conditions or are not amenable at all to photoredox transformations. In this work, we show that strong bis-cyclometalated iridium photoreductants with electron-rich β-diketiminate (NacNac) ancillary ligands enable high-yielding photoredox transformations of challenging substrates with very simple reaction conditions that require only a single sacrificial reagent. Using blue or green visible-light activation we demonstrate a variety of reactions, which include hydrodehalogenation, cyclization, intramolecular radical addition, and prenylation radical-mediated pathways, with optimized conditions that only require the photocatalyst and a sacrificial reductant/hydrogen atom donor. Many of these reactions involve organobromide and organochloride substrates which in the past have had limited utility in photoredox catalysis. This work paves the way for the continued expansion of the substrate scope in photoredox catalysis.
光氧化还原催化已成为有机合成化学中的一种强大策略,但难以还原的底物要么需要复杂的反应条件,要么根本不适合光氧化还原转化。在这项工作中,我们表明,具有富电子β-二酮亚胺(NacNac)辅助配体的强双环金属化铱光还原剂,能够在非常简单的反应条件下实现具有挑战性底物的高产率光氧化还原转化,这些条件仅需一种牺牲试剂。通过蓝色或绿色可见光活化,我们展示了多种反应,包括加氢脱卤、环化、分子内自由基加成和异戊烯基化等自由基介导的途径,其优化条件仅需光催化剂和一种牺牲还原剂/氢原子供体。这些反应中有许多涉及有机溴化物和有机氯化物底物,而它们过去在光氧化还原催化中的应用有限。这项工作为光氧化还原催化中底物范围的持续扩展铺平了道路。