C−H and C−N Activation at Redox-Active Pyridine Complexes of Iron
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- 作者：K. Cory MacLeod ; Richard A. Lewis ; Daniel E. DeRosha ; Brandon Q. Mercado and Patrick L. Holland
- 刊名：Angewandte Chemie
- 出版年：2017
- 出版时间：January 19, 2017
- 年：2017
- 卷：129
- 期：4
- 页码：1089-1092
- 全文大小：835K
- ISSN：1521-3757
文摘
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.