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

Alberto Hernán-Gómez, Emma Herd, Eva Hevia, Alan R. Kennedy, Paul Knochel, Konrad Koszinowski, Sophia M. Manolikakes, Robert E. Mulvey, Christoph Schnegelsberg

Research output: Contribution to journalArticle

48 Citations (Scopus)
228 Downloads (Pure)

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].
Original languageEnglish
Pages (from-to)2706–2710
Number of pages5
JournalAngewandte Chemie International Edition
Volume53
Issue number10
Early online date31 Jan 2014
DOIs
Publication statusPublished - 3 Mar 2014

Keywords

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

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