l-Proline derived mimics of the non-haem iron active site catalyse allylic oxidation in acetonitrile solutions

Dungan, Victoria J.; Poon, Belinda M.-L.; Barrett, Elizabeth S.; Rutledge, Peter J.

doi:10.1016/j.tetlet.2012.12.095

Cited by 7 publications

(7 citation statements)

References 34 publications

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“…L-proline derived ligands 61, 62a, and 62b were designed to mimic the coordination environment of nonheme iron enzymes, but instead of achieving a metalcentred oxidation mechanism, cyclohexene is oxidised via a radical mechanism in allylic position. 139 A high-valent iron-oxo species could be observed spectroscopically and by mass spectrometry during hydrocarbon oxidation by iron complexes bearing the independent ligands 55b and Racac (63, Figure 10) with oxone. 140 The combination of a neutral, robust N-donor and the redox active acetylacetonate (acac) derivative allows even the oxidation of challenging substrates such as ethane and propane.…”

Section: Iron Nonheme Complexes Bearing C- O-and S-donor Ligandsmentioning

confidence: 99%

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

2015

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The selective oxygenation of C-H bonds is a promising and interesting task for both academia and chemical industry. Inspired by the efficiency and selectivity of naturally occurring enzymes, iron heme and nonheme complexes have proven to be valuable candidates for the development of environmentally friendly catalysts as alternative to traditional systems. This feature article summarises developments of the last decade regarding oxygenation reactions of aliphatic and aromatic substrates with various oxidants catalysed by molecular iron complexes. With a special focus on the catalytic performance of the systems, both the potential and the limitations as well as mechanistic aspects are discussed in some detail.

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Section: Iron Nonheme Complexes Bearing C- O-and S-donor Ligandsmentioning

confidence: 99%

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

2015

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“…As an extension of our previously reported iron-catalysed allylic oxidation of cyclohexene ( 7 ) [ 45 – 47 ], we wished to explore potential C–N bond formation at this position using iron catalysis. Combining cyclohexene ( 7 , in excess) with N -Boc-hydroxylamine ( 8 ) as the nitrogen source and the iron complex FeTPA ( 4 ) or FeBPMEN ( 5 ) afforded a mixture of products: the allylic hydroxylamine 9 alongside the Fenton oxidation products alcohol 10 and ketone 11 [ 53 ], and a small amount of tert- butyl carbamate ( 12 , Scheme 1 ).…”

Section: Resultsmentioning

confidence: 99%

“…Using a 1:1:1 ratio of cyclohexene:BocNHOH:H 2 O 2 with FeTPA ( 4 ) at 1 mol %, allylic hydroxylamine 9 was formed in only 4% yield, with the allylic oxidation products 9 and 10 predominant. This is not unexpected given the propensity of hydrogen peroxide to react directly with iron complexes to produce 10 and 11 via Fenton-type pathways [ 47 , 53 ].…”

Section: Resultsmentioning

confidence: 99%

“…Stemming from our interest in iron-catalysed hydrocarbon oxidation using systems inspired by the non-heme iron-dependent enzyme family [ 42 – 47 ], we have investigated the capacity of iron complexes of simple tetramine ligands to promote the reaction between an alkene and N -Boc-hydroxylamine. Herein we report that iron complexes of tris(2-pyridylmethyl)amine (TPA, 1 ) [ 48 – 49 ], N , N ′-bis(2-pyridylmethyl)- N , N ′-dimethylethane-1,2-diamine (BPMEN, 2 ) [ 48 , 50 ] and (+)-(2 R ,2′ R )-1,1′-bis(2-pyridylmethyl)-2,2′-bipyrrolidine (( R , R ′)-PDP, 3 ) [ 51 ] ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

Porter¹,

Poon²,

Rutledge³

2015

Beilstein J. Org. Chem.

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SummaryIron(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).

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“…Amides of general structures 1 and 2 ( Figure 1 ) have a range of potential applications as ligands for catalysis, in molecular switches, and as metal binding agents. When combined with iron(II), ligands of this ilk can promote alkene dihydroxylation and allylic oxidation reactions akin to those mediated by non-heme iron oxidase enzymes (NHIOs) 1 2 3 4 5 6 7 8 9 ; in combination with cobalt(III) or iron(III), they may catalyse conversion of nitriles to primary amide products, as mimics of the metalloenzyme nitrile hydratase 10 11 12 13 .…”

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Synthesis and structural characterisation of amides from picolinic acid and pyridine-2,6-dicarboxylic acid

Devi

Barry

Houlihan

et al. 2015

Sci Rep

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Coupling picolinic acid (pyridine-2-carboxylic acid) and pyridine-2,6-dicarboxylic acid with N-alkylanilines affords a range of mono- and bis-amides in good to moderate yields. These amides are of interest for potential applications in catalysis, coordination chemistry and molecular devices. The reaction of picolinic acid with thionyl chloride to generate the acid chloride in situ leads not only to the N-alkyl-N-phenylpicolinamides as expected but also the corresponding 4-chloro-N-alkyl-N-phenylpicolinamides in the one pot. The two products are readily separated by column chromatography. Chlorinated products are not observed from the corresponding reactions of pyridine-2,6-dicarboxylic acid. X-Ray crystal structures for six of these compounds are described. These structures reveal a general preference for cis amide geometry in which the aromatic groups (N-phenyl and pyridyl) are cis to each other and the pyridine nitrogen anti to the carbonyl oxygen. Variable temperature 1H NMR experiments provide a window on amide bond isomerisation in solution.

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l-Proline derived mimics of the non-haem iron active site catalyse allylic oxidation in acetonitrile solutions

Cited by 7 publications

References 34 publications

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

Molecular iron complexes as catalysts for selective C–H bond oxygenation reactions

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

Synthesis and structural characterisation of amides from picolinic acid and pyridine-2,6-dicarboxylic acid

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