C−H and C−N Activation at Redox‐Active Pyridine Complexes of Iron. Issue 4 (21st December 2016)

• Record Type: Journal Article
• Authors: MacLeod, K. Cory; Lewis, Richard A.; DeRosha, Daniel E.; Mercado, Brandon Q.; Holland, Patrick L.
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 4(2017)
• Page Start: 1069
• Page End: 1072
• Publication Date: 2016-12-21
• Subjects: bond cleavage -- iron -- pyridine -- redox-activity; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201610679
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Pyridine activation by inexpensive iron catalysts has great utility, but the steps through which iron species can break the strong (105–111 kcal mol −1 ) C−H bonds of pyridine substrates are unknown. In this work, we report the rapid room‐temperature cleavage of C−H bonds in pyridine, 4‐tert‐butylpyridine, and 2‐phenylpyridine by an iron(I) species, to give well‐characterized iron(II) products. In addition, 4‐dimethylaminopyridine (DMAP) undergoes room‐temperature C−N bond cleavage, which forms a dimethylamidoiron(II) complex and a pyridyl‐bridged tetrairon(II) square. These facile bond‐cleaving reactions are proposed to occur through intermediates having a two‐electron reduced pyridine that bridges two iron centers. Thus, the redox non‐innocence of the pyridine can play a key role in enabling high regioselectivity for difficult reactions. Abstract : An iron(I) complex activates C−H and C−N bonds in pyridines, using a mechanism that takes advantage of pyridine's redox activity. The bond‐cleaving reactions are proposed to occur through intermediates with a two‐electron reduced pyridine that bridges two iron centers.