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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.

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

Reaction between lithium bis(piperidido)cuprate(I) and iodobenzene. Yields were determined by NMR spectroscopy using mesitylene as an internal standard. Yields are reported as a mean of at least two independent runs.
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fig11: Reaction between lithium bis(piperidido)cuprate(I) and iodobenzene. Yields were determined by NMR spectroscopy using mesitylene as an internal standard. Yields are reported as a mean of at least two independent runs.

Mentions: The effect of phen on the reactivity of 3 was more pronounced when [D6]DMSO was used as the solvent, with the yield unexpectedly decreasing from 75 % to 26 %. The yields obtained with complexes 4 and 5 on addition of phen were also diminished in [D6]DMSO compared to their ligand-free analogues. These results are somewhat surprising in light of the prominent role played by phen in copper-catalysed Ullmann amination.[4–9] Nevertheless, they can be explained in the context of the solution studies which showed the favoured formation of the ionic cuprate species (III, Scheme 4) on addition of phen to copper(I) amide in DMSO. Previous studies on the reactivity of isolated bisamidocuprate complexes [Cu(NR2)2]− (NR2=NPh2;[30] phthalimidate[29]) have shown these anionic species to have little or no reactivity in the cross-coupling reaction with aryl halides. If, as seems likely, the bis(dialkylamino)cuprate complexes present in the reaction mixture here also exhibit low reactivity, this could help explain the observed reduction in product yield. To verify this theory, lithium bis(piperidido)cuprate(I) was prepared (by the reaction of CuI and two equivalents of lithium piperidide) and then treated with iodobenzene (Scheme 5). Conversions obtained from this reaction were very low (<2 %), thus confirming bis(dialkylamido)cuprates to also be relatively inert in the C—N coupling reaction.


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)

Reaction between lithium bis(piperidido)cuprate(I) and iodobenzene. Yields were determined by NMR spectroscopy using mesitylene as an internal standard. Yields are reported as a mean of at least two independent runs.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig11: Reaction between lithium bis(piperidido)cuprate(I) and iodobenzene. Yields were determined by NMR spectroscopy using mesitylene as an internal standard. Yields are reported as a mean of at least two independent runs.
Mentions: The effect of phen on the reactivity of 3 was more pronounced when [D6]DMSO was used as the solvent, with the yield unexpectedly decreasing from 75 % to 26 %. The yields obtained with complexes 4 and 5 on addition of phen were also diminished in [D6]DMSO compared to their ligand-free analogues. These results are somewhat surprising in light of the prominent role played by phen in copper-catalysed Ullmann amination.[4–9] Nevertheless, they can be explained in the context of the solution studies which showed the favoured formation of the ionic cuprate species (III, Scheme 4) on addition of phen to copper(I) amide in DMSO. Previous studies on the reactivity of isolated bisamidocuprate complexes [Cu(NR2)2]− (NR2=NPh2;[30] phthalimidate[29]) have shown these anionic species to have little or no reactivity in the cross-coupling reaction with aryl halides. If, as seems likely, the bis(dialkylamino)cuprate complexes present in the reaction mixture here also exhibit low reactivity, this could help explain the observed reduction in product yield. To verify this theory, lithium bis(piperidido)cuprate(I) was prepared (by the reaction of CuI and two equivalents of lithium piperidide) and then treated with iodobenzene (Scheme 5). Conversions obtained from this reaction were very low (<2 %), thus confirming bis(dialkylamido)cuprates to also be relatively inert in the C—N coupling reaction.

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