美国马里兰大学Osvaldo Gutierrez团队最新研究探明了铁催化多组分自由基级联-交叉偶联的通用方法。相关研究成果发表在2021年10月22日出版的《科学》。

过渡金属催化的交叉偶联反应是化学合成中应用最广泛的方法之一。然而，尽管铁（Fe）作为一种潜在的更便宜、更丰富、毒性更小的过渡金属催化剂具有显著的优势，但其在多组分交叉耦合中的实际应用仍然不成功。

研究人员证明了1,2-双（二环己基膦）乙烷铁催化α-硼基自由基（由硼酸乙烯基选择性自由基加成生成）与格氏试剂的偶联。然后，研究人员通过开发一种通用且广泛适用的铁催化多组分环化-交叉耦合协议扩展了这些自由基级联的范围，该协议涉及广泛的π-系统，并能够实际合成环氟化合物。机理研究与双芳基化Fe（II）物种负责生成烷基自由基以启动催化一致，而单芳基化Fe（II）中心和瞬时烷基自由基之间进行碳-碳键形成。

附：英文原文

Title: General method for iron-catalyzed multicomponent radical cascades–cross-couplings

Author: Lei Liu, Maria Camila Aguilera, Wes Lee, Cassandra R. Youshaw, Michael L. Neidig, Osvaldo Gutierrez

Issue&Volume: 2021-10-22

Abstract: Transition metal–catalyzed cross-coupling reactions are some of the most widely used methods in chemical synthesis. However, despite notable advantages of iron (Fe) as a potentially cheaper, more abundant, and less toxic transition metal catalyst, its practical application in multicomponent cross-couplings remains largely unsuccessful. We demonstrate 1,2-bis(dicyclohexylphosphino)ethane Fe–catalyzed coupling of α-boryl radicals (generated from selective radical addition to vinyl boronates) with Grignard reagents. Then, we extended the scope of these radical cascades by developing a general and broadly applicable Fe-catalyzed multicomponent annulation–cross-coupling protocol that engages a wide range of π-systems and permits the practical synthesis of cyclic fluorous compounds. Mechanistic studies are consistent with a bisarylated Fe(II) species being responsible for alkyl radical generation to initiate catalysis, while carbon-carbon bond formation proceeds between a monoarylated Fe(II) center and a transient alkyl radical.

DOI: abj6005

Source: https://www.science.org/doi/10.1126/science.abj6005