title: Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso-ene mechanism.
abstract: Iron(II) complexes of the tetradentate amines tris(2-pyridylmethyl)amine (TPA) and N,N'-bis(2-pyridylmethyl)-N,N'-dimethylethane-1,2-diamine (BPMEN) are established catalysts of C-O bond formation, oxidising hydrocarbon substrates via hydroxylation, epoxidation and dihydroxylation pathways. Herein we report the capacity of these catalysts to promote C-N bond formation, via allylic amination of alkenes. The combination of N-Boc-hydroxylamine with either FeTPA (1 mol %) or FeBPMEN (10 mol %) converts cyclohexene to the allylic hydroxylamine (tert-butyl cyclohex-2-en-1-yl(hydroxy)carbamate) in moderate yields. Spectroscopic studies and trapping experiments suggest the reaction proceeds via a nitroso-ene mechanism, with involvement of a free N-Boc-nitroso intermediate. Asymmetric induction is not observed using the chiral tetramine ligand (+)-(2R,2'R)-1,1'-bis(2-pyridylmethyl)-2,2'-bipyrrolidine ((R,R')-PDP).
authors.affiliation: School of Chemistry F11, The University of Sydney, NSW 2006, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Porter
authors.affiliation: School of Chemistry F11, The University of Sydney, NSW 2006, Australia.
authors.forename: Belinda M-L
authors.initials: BM
authors.lastname: Poon
authors.affiliation: School of Chemistry F11, The University of Sydney, NSW 2006, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Rutledge
keywords: CH activation; hydroxyamination; iron catalysis; nitroso-ene