Alkali-metal-mediated magnesiations of an N-heterocyclic carbene: normal, abnormal and "paranormal" reactivity in a single tritopic molecule

Antonio J. Martínez-Martínez, M. Ángeles Fuentes, Alberto Hernán-Gõmez, Eva Hevia, Alan R. Kennedy, Robert E. Mulvey, Charles T. O'Hara

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)
118 Downloads (Pure)

Abstract

Herein the sodium alkylmagnesium amide [Na4Mg2(TMP)6(nBu)2] (TMP=2,2,6,6-tetramethylpiperidide), a template base as its deprotonating action is dictated primarily by its 12 atom ring structure, is studied with the common N-heterocyclic carbene (NHC) IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. Remarkably, magnesiation of IPr occurs at the para-position of an aryl substituent, sodiation occurs at the abnormal C4 position, and a dative bond occurs between normal C2 and sodium, all within a 20 atom ring structure accommodating two IPr2-. Studies with different K/Mg and Na/Mg bimetallic bases led to two other magnesiated NHC structures containing two or three IPr- monoanions bound to Mg through abnormal C4 sites. Synergistic in that magnesiation can only work through alkali-metal mediation, these reactions add magnesium to the small cartel of metals capable of directly metalating a NHC.

Original languageEnglish
Pages (from-to)14075-14079
Number of pages5
JournalAngewandte Chemie International Edition
Volume54
Issue number47
Early online date29 Sep 2015
DOIs
Publication statusPublished - 16 Nov 2015

Keywords

  • alkali metals
  • carbenes
  • crown compounds
  • magnesium
  • metalation

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