Organozinc pivalate reagents: segregation, solubility, stabilisation and structural insights

Alberto Hernan-Gomez, Emma Herd, Eva Hevia, Alan Kennedy, Paul Knochel, Konrad Koszinowski, Sophia M. Manolikakes, Christoph Schnegelsberg, Robert Mulvey

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

The pivalates RZnOPiv⋅Mg(OPiv)X⋅n LiCl (OPiv=pivalate; R=aryl; X=Cl, Br, I) stand out amongst salt-supported organometallic reagents, because apart from their effectiveness in Negishi cross-coupling reactions, they show more resistance to attack by moist air than conventional organometallic compounds. Herein a combination of synthesis, coupling applications, X-ray crystallographic studies, NMR (including DOSY) studies, and ESI mass spectrometric studies provide details of these pivalate reagents in their own right. A p-tolyl case system shows that in [D8]THF solution these reagents exist as separated Me(p-C6H4)ZnCl and Mg(OPiv)2 species. Air exposure tests and X-ray crystallographic studies indicate that Mg(OPiv)2 enhances the air stability of aryl zinc species by sequestering H2O contaminants. Coupling reactions of Me(p-C6H4)ZnX (where X=different salts) with 4-bromoanisole highlight the importance of the presence of Mg(OPiv)2. Insight into the role of LiCl in these multicomponent mixtures is provided by the molecular structure of [(THF)2Li2(Cl)2(OPiv)2Zn].
LanguageEnglish
Pages2706–2710
Number of pages5
JournalAngewandte Chemie International Edition
Volume53
Early online date25 Feb 2014
DOIs
Publication statusPublished - 3 Mar 2014

Fingerprint

Solubility
Stabilization
Air
Salts
Organometallic Compounds
X-Rays
X rays
Cross Reactions
Organometallics
Molecular Structure
Molecular structure
Zinc
Nuclear magnetic resonance
Impurities

Keywords

  • reagents
  • organozinc
  • pivalate
  • segregation
  • stabilisation
  • solubility
  • structural insights
  • salt effect
  • structure elucidation
  • cross-coupling
  • organomagnesium reagents
  • organozinc reagents

Cite this

Hernan-Gomez, Alberto ; Herd, Emma ; Hevia, Eva ; Kennedy, Alan ; Knochel, Paul ; Koszinowski, Konrad ; Manolikakes, Sophia M. ; Schnegelsberg, Christoph ; Mulvey, Robert. / Organozinc pivalate reagents : segregation, solubility, stabilisation and structural insights. In: Angewandte Chemie International Edition. 2014 ; Vol. 53. pp. 2706–2710.
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abstract = "The pivalates RZnOPiv⋅Mg(OPiv)X⋅n LiCl (OPiv=pivalate; R=aryl; X=Cl, Br, I) stand out amongst salt-supported organometallic reagents, because apart from their effectiveness in Negishi cross-coupling reactions, they show more resistance to attack by moist air than conventional organometallic compounds. Herein a combination of synthesis, coupling applications, X-ray crystallographic studies, NMR (including DOSY) studies, and ESI mass spectrometric studies provide details of these pivalate reagents in their own right. A p-tolyl case system shows that in [D8]THF solution these reagents exist as separated Me(p-C6H4)ZnCl and Mg(OPiv)2 species. Air exposure tests and X-ray crystallographic studies indicate that Mg(OPiv)2 enhances the air stability of aryl zinc species by sequestering H2O contaminants. Coupling reactions of Me(p-C6H4)ZnX (where X=different salts) with 4-bromoanisole highlight the importance of the presence of Mg(OPiv)2. Insight into the role of LiCl in these multicomponent mixtures is provided by the molecular structure of [(THF)2Li2(Cl)2(OPiv)2Zn].",
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Organozinc pivalate reagents : segregation, solubility, stabilisation and structural insights. / Hernan-Gomez, Alberto; Herd, Emma; Hevia, Eva; Kennedy, Alan; Knochel, Paul ; Koszinowski, Konrad ; Manolikakes, Sophia M. ; Schnegelsberg, Christoph ; Mulvey, Robert.

In: Angewandte Chemie International Edition, Vol. 53, 03.03.2014, p. 2706–2710.

Research output: Contribution to journalArticle

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KW - cross-coupling

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