Although divalent Sm reagents are some of the most important single-electron transfer reagents for reductive transformations, their catalytic applications are challenging. In this study, a bidentate phosphine oxide ligand substituted with 9,10-diphenylanthracene as a visible-light antenna was designed for Sm-catalyzed reduction reactions under mild reaction conditions. Pinacol coupling of aryl ketones and aldehydes was developed with 1 mol % of Sm catalyst and organic amine (DIPEA) as a sacrificial mild reductant. Mechanistic studies suggest that the visible-light-antenna ligand coordinates to Sm(III) and reduces Sm(III) to Sm(II) under visible-light irradiation. The catalytic system is also applicable for cross-pinacol coupling and other single-electron reductive transformations, including aza-pinacol coupling, flavone dimerization, C–O bond cleavage, C–C ring-opening of cyclopropane, ketyl-olefin coupling, and cross-coupling of the ketyl radical with the α-amino radical.

中文翻译：

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可见光天线配体钐催化还原转化


尽管二价 Sm 试剂是还原转化中最重要的单电子转移试剂之一，但它们的催化应用具有挑战性。在这项研究中，设计了一种被9,10-二苯基蒽取代的二齿氧化膦配体作为可见光天线，用于温和反应条件下的Sm催化还原反应。使用 1 mol% 的 Sm 催化剂和有机胺 (DIPEA) 作为牺牲性温和还原剂，开发了芳基酮和醛的频哪醇偶联反应。机理研究表明，可见光天线配体在可见光照射下与Sm(III)配位并将Sm(III)还原为Sm(II)。该催化体系还适用于交叉频哪醇偶联和其他单电子还原转化，包括氮杂频哪醇偶联、黄酮二聚、C-O键断裂、环丙烷C-C开环、羰基-烯烃偶联和交叉反应。 -羰基与α-氨基的偶联。