Brewer Samantha M, Schwartz Timothy M, Mekhail Magy A, Turan Lara S, Prior Timothy J, Hubin Timothy J, Janesko Benjamin G, Green Kayla N
Department of Chemistry and Biochemistry, Texas Christian University, Fort Worth, Texas 76129, United States.
Department of Chemistry and Biochemistry, University of Hull, Hull HU6 7RX, U.K.
Organometallics. 2021 Aug 9;40(15):2467-2477. doi: 10.1021/acs.organomet.1c00211. Epub 2021 Jul 20.
Iron-catalyzed C-C coupling reactions of pyrrole provide a unique alternative to the traditional Pd-catalyzed counterpart. However, many details regarding the actual mechanism remain unknown. A series of macrocyclic iron(III) complexes were used to evaluate specifics related to the role of O, radicals, and -oxodiiron-complex participation in the catalytic cycle. It was determined that the mononuclear tetra-azamacrocyclic complex is a true catalyst and not a stoichiometric reagent, while more than one equivalent of a sacrificial oxidant is needed. Furthermore, the reaction does not proceed through an organic radical pathway. -Oxodiiron complexes are not involved in the main catalytic pathway, and the dimers are, in fact, off-cycle species that decrease catalytic efficiency.
铁催化的吡咯碳-碳偶联反应为传统钯催化反应提供了一种独特的替代方法。然而，关于实际反应机理的许多细节仍不清楚。一系列大环铁（III）配合物被用于评估与氧、自由基以及双铁氧配合物参与催化循环的作用相关的具体情况。已确定单核四氮大环配合物是真正的催化剂而非化学计量试剂，同时需要超过一当量的牺牲性氧化剂。此外，该反应并非通过有机自由基途径进行。双铁氧配合物不参与主要催化途径，实际上二聚体是降低催化效率的非循环物种。
