Structurally powered synergic 2,2,6,6-tetramethylpiperidine bimetallics: new reflections through lithium-mediated ortho aluminations

Robert Mulvey, David R. Armstrong, Ben Conway, Elaine Crosbie, Alan Kennedy, Stuart Robertson

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Recent times have witnessed many notable advances in metalation chemistry with halide salt supported strategies and alkali-metal mediated metalation being particularly prominent. This article begins with a brief account of both of these avant garde metalation methods focusing on selected recent examples not covered previously in a review. New results in the area of Alkali-Metal Mediated Alumination (AMMAl) are also presented. Thus, the putative lithium aluminate base THE center dot Li(mu-TMP)(2)Al(Bu-i)(2) (4) is shown to act via TMP basicity to efficiently ortho deprotonate a variety of functionalized aromatic molecules at room temperature, tolerating carboxamide and halide functionalities. These metalated species are electrophilically quenched with elemental iodine. Crystal structure determinations of the metalated intermediates confirm unequivocally that direct alumination of the substrates has occurred. Since the homometallic lithium or aluminum reagents are unable to effect such deprotonations these reactions are synergic in nature and can be considered examples of AMMAl. Drawing together previously published work in the field of AMMAl, together with other pertinent experimental Observations and new density functional theory (DFT) computational studies, we propose a potential rationale for the "unusual" reactivity patterns witnessed in this branch of heterometallic synthetic chemistry with respect to other Alkali Metal Mediated Metalations which appear to behave in a more conventional manner.

Original languageEnglish
Pages (from-to)12241-12251
Number of pages11
JournalInorganic Chemistry
Volume50
Issue number24
DOIs
Publication statusPublished - 19 Dec 2011

Keywords

  • directed ortho-metalation
  • chemoselective functionalization
  • aluminium compounds
  • INVERSE CROWN CHEMISTRY
  • DEPROTONATIVE METALATION
  • crystal structures
  • zincation

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