Facilitating the Ferration of Aromatic Substrates through Intramolecular Sodium Mediation

Lewis C H Maddock; Manting Mu; Alan R Kennedy; Max García-Melchor; Eva Hevia

doi:10.1002/anie.202104275

Facilitating the Ferration of Aromatic Substrates through Intramolecular Sodium Mediation

Angew Chem Int Ed Engl. 2021 Jul 5;60(28):15296-15301. doi: 10.1002/anie.202104275. Epub 2021 Jun 17.

Authors

Lewis C H Maddock¹, Manting Mu², Alan R Kennedy³, Max García-Melchor², Eva Hevia¹

Affiliations

¹ Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland.
² School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, College Green, Dublin, 2, Ireland.
³ Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral St, Glasgow, G11XL, UK.

Abstract

Exploiting cooperative effects between Na and Fe^II centres present in tris(amide) ferrate complexes has led to the chemoselective ferration of pentafluorobenzene, benzene, toluene, anisole, and pyridine being realised at room temperature. The importance of this bimetallic partnership is demonstrated by neither the relevant sodium amide (NaHMDS or NaTMP) nor the Fe^II amide Fe(HMDS)₂ efficiently metallating these substrates under the conditions of this study. By combining NMR studies with the isolation of key intermediates and DFT calculations, we offer a possible mechanism for how these reactions take place, uncovering a surprising reaction pathway in which the metals cooperate in a synchronised manner. Although the isolated products are formally the result of Fe-H exchange, theoretical calculations indicate that the aromatic substrates undergo Na-H exchange followed by fast intramolecular transmetallation to Fe, thus stabilizing the newly generated aryl fragment.

Keywords: DFT calculations; cooperative effects; iron; metallation; sodium.

Publication types

Research Support, Non-U.S. Gov't