Structural and synthetic insights into sodium‐mediated‐ferration of fluoroarenes

Lewis C. H. Maddock, Alan R. Kennedy, Eva Hevia

Research output: Contribution to journalArticlepeer-review

Abstract

Exploiting chemical cooperation between Na and Fe(II) within the bimetallic base [dioxane ⋅ NaFe(HMDS) 3] (I), (dioxane=1,4-dioxane, HMDS=N(SiMe 3) 2) the selective ferration of fluorobenzene, 1-fluoronaphthalene, 1,4-difluorobenzene, 1,2,4-trifluorobenzene, 1,3,5-trifluorobenzene, 1-bromo-3,5-difluorobenzene, 3-fluoroanisole and 3,5-difluoroanisole has been realized, affording sodium ferrates [dioxane ⋅ Na(HMDS)(2-F-C 6H 4)Fe(HMDS)] (1), [dioxane ⋅ Na(HMDS)(2-F-C 10H 6)Fe(HMDS)] (2), [dioxane ⋅ {Na(HMDS)(2,5-F 2-C 6H 3)Fe(HMDS)} 2] (3), [dioxane ⋅ {Na(HMDS)(2,3,6-F 3-C 6H 2)Fe(HMDS)} 2] (4), [(dioxane) 1.5 ⋅ Na(HMDS)(2,4,6-F 3-C 6H 2)Fe(HMDS)] 2 (5), [(dioxane) 1.5 ⋅ {Na(HMDS)(4-Br-2,6-F 2-C 6H 2)Fe(HMDS) 2] (6), [{(dioxane) 2 ⋅ Na 2Fe(HMDS) 2(2-methoxy-6-F-C 6H 3)} +{Fe(HMDS) 3} ] (7) and [dioxane ⋅ {Na(HMDS)(4-methoxy-2,6-F 2-C 6H 2)Fe(HMDS)} 2] (8), respectively. Reactions take place under mild reaction conditions, with excellent control of the selectivity and no competing C−F bond activation is observed. Showcasing complex polymeric arrangements in some cases, the structures of compounds 1–8 have been determined by X-ray crystallographic studies. In all cases, the Fe(II) centers occupy the position in the relevant fluoroarene that was previously filled by a proton, confirming that these metallations are actually ferration processes whereas the Na atoms prefer to form Na⋅⋅⋅F dative interactions. Compounds 1–8 are thermally stable and do not undergo benzyne formation (through NaF elimination) and their formation contrasts with the inertness of Fe(HMDS) 2 which fails to act as a base to metallate fluoroarenes.

Original languageEnglish
Article numbere2100206
Number of pages9
JournalHelvetica Chimica Acta
Volume104
Issue number12
Early online date29 Oct 2021
DOIs
Publication statusE-pub ahead of print - 29 Oct 2021

Keywords

  • ferrates
  • sodium
  • cooperative effects
  • fluoroarenes
  • metallation

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