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Synthesis, characterisation and reactivity of copper(I) amide complexes and studies on their role in the modified Ullmann amination reaction.

Sung S, Braddock DC, Armstrong A, Brennan C, Sale D, White AJ, Davies RP - Chemistry (2015)

Bottom Line: Complexes 1, 2 and 4 are shown to exist as tetramers in the solid state by X-ray crystallography.In [D6 ]benzene solution, complexes 1, 2 and 5 were found by using (1) H DOSY NMR to exist in rapid equilibrium between aggregates with average aggregation numbers of 2.5, 2.4 and 3.3, respectively, at 0.05 M concentration.The role of phenanthroline has also been explored both in the stoichiometric reaction and in the catalytic Ullmann protocol.

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Affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ (UK).

No MeSH data available.


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General reaction scheme of the modified Ullmann reaction
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fig07: General reaction scheme of the modified Ullmann reaction

Mentions: Copper mediated cross-coupling reactions between aryl halides and amines to form carbon-nitrogen bonds were first reported over a century ago by Ullmann when he demonstrated the preparation of 2-(N-phenylamino)benzoic acid from o-chlorobenzoic acid and aniline in the presence of stoichiometric copper metal.[1] However, this classical method for cross-coupling aryl halides and amines has many drawbacks including high (stoichiometric) copper metal loadings, high reaction temperatures and also long reaction times.[2, 3] More recently new protocols that incorporate the use of bidentate ligands such as 1,10-phenanthroline (phen)[4–9] have enabled these reactions to be carried out at lower reaction temperatures (≤110 °C) with lower copper loadings (≤10 %).[10–13] This improved copper-catalysed reaction is commonly referred to as the modified Ullmann amination reaction (Scheme 1).


Synthesis, characterisation and reactivity of copper(I) amide complexes and studies on their role in the modified Ullmann amination reaction.

Sung S, Braddock DC, Armstrong A, Brennan C, Sale D, White AJ, Davies RP - Chemistry (2015)

General reaction scheme of the modified Ullmann reaction
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4471577&req=5

fig07: General reaction scheme of the modified Ullmann reaction
Mentions: Copper mediated cross-coupling reactions between aryl halides and amines to form carbon-nitrogen bonds were first reported over a century ago by Ullmann when he demonstrated the preparation of 2-(N-phenylamino)benzoic acid from o-chlorobenzoic acid and aniline in the presence of stoichiometric copper metal.[1] However, this classical method for cross-coupling aryl halides and amines has many drawbacks including high (stoichiometric) copper metal loadings, high reaction temperatures and also long reaction times.[2, 3] More recently new protocols that incorporate the use of bidentate ligands such as 1,10-phenanthroline (phen)[4–9] have enabled these reactions to be carried out at lower reaction temperatures (≤110 °C) with lower copper loadings (≤10 %).[10–13] This improved copper-catalysed reaction is commonly referred to as the modified Ullmann amination reaction (Scheme 1).

Bottom Line: Complexes 1, 2 and 4 are shown to exist as tetramers in the solid state by X-ray crystallography.In [D6 ]benzene solution, complexes 1, 2 and 5 were found by using (1) H DOSY NMR to exist in rapid equilibrium between aggregates with average aggregation numbers of 2.5, 2.4 and 3.3, respectively, at 0.05 M concentration.The role of phenanthroline has also been explored both in the stoichiometric reaction and in the catalytic Ullmann protocol.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ (UK).

No MeSH data available.


Related in: MedlinePlus