title: Redox-neutral α-oxygenation of amines: reaction development and elucidation of the mechanism.
abstract: Cyclic secondary amines and 2-hydroxybenzaldehydes or related ketones react to furnish benzo[e][1,3]oxazine structures in generally good yields. This overall redox-neutral amine α-C-H functionalization features a combined reductive N-alkylation/oxidative α-functionalization and is catalyzed by acetic acid. In contrast to previous reports, no external oxidants or metal catalysts are required. Reactions performed under modified conditions lead to an apparent reductive amination and the formation of o-hydroxybenzylamines in a process that involves the oxidation of a second equivalent of amine. A detailed computational study employing density functional theory compares different mechanistic pathways and is used to explain the observed experimental findings. Furthermore, these results also reveal the origin of the catalytic efficiency of acetic acid in these transformations.
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , Piscataway, New Jersey 08854, United States.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Richers
authors.forename: Martin
authors.initials: M
authors.lastname: Breugst
authors.forename: Alena Yu
authors.initials: AY
authors.lastname: Platonova
authors.forename: Anja
authors.initials: A
authors.lastname: Ullrich
authors.forename: Arne
authors.initials: A
authors.lastname: Dieckmann
authors.forename: K N
authors.initials: KN
authors.lastname: Houk
authors.forename: Daniel
authors.initials: D
authors.lastname: Seidel
mesh_terms: D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D007659:Ketones / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D014050:Toluene / Q000737:chemistry
chemical_list: D000588:Amines; D007659:Ketones; D014050:Toluene; D010100:Oxygen