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Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyltroponeiron
Published on: August 12, 2019
TMEDA in iron-catalyzed Kumada coupling: amine adduct versus homoleptic "ate" complex formation
Robin B Bedford1, Peter B Brenner, Emma Carter
1School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS (UK). r.bedford@bristol.ac.uk.
Abstract:
The reactions of iron chlorides with mesityl Grignard reagents and tetramethylethylenediamine (TMEDA) under catalytically relevant conditions tend to yield the homoleptic "ate" complex [Fe(mes)3 ](-) (mes=mesityl) rather than adducts of the diamine, and it is this ate complex that accounts for the catalytic activity. Both [Fe(mes)3 ](-) and the related complex [Fe(Bn)3 ](-) (Bn=benzyl) react faster with representative electrophiles than the equivalent neutral [FeR2 (TMEDA)] complexes. Fe(I) species are observed under catalytically relevant conditions with both benzyl and smaller aryl Grignard reagents. The X-ray structures of [Fe(Bn)3 ](-) and [Fe(Bn)4 ](-) were determined; [Fe(Bn)4 ](-) is the first homoleptic σ-hydrocarbyl Fe(III) complex that has been structurally characterized.
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