title: C-H and C-N Activation at Redox-Active Pyridine Complexes of Iron.
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.
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, 06520, USA.
authors.forename: K Cory
authors.initials: KC
authors.lastname: MacLeod
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, 06520, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Lewis
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, 06520, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: DeRosha
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, 06520, USA.
authors.forename: Brandon Q
authors.initials: BQ
authors.lastname: Mercado
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, 06520, USA.
authors.forename: Patrick L
authors.identifier: 0000-0002-2883-2031
authors.initials: PL
authors.lastname: Holland
mesh_terms: D005296:Ferrous Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*
chemical_list: D005296:Ferrous Compounds; D011725:Pyridines; C023666:pyridine
keywords: bond cleavage; iron; pyridine; redox-activity