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The Effect of β‐Hydrogen Atoms on Iron Speciation in Cross‐Couplings with Simple Iron Salts and Alkyl Grignard Reagents
Author(s) -
Sears Jeffrey D.,
Muñoz Salvador B.,
Daifuku Stephanie L.,
Shaps Ari A.,
Carpenter Stephanie H.,
Brennessel William W.,
Neidig Michael L.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201813578
Subject(s) - chemistry , nucleophile , alkyl , electrophile , ferric , reagent , metal , reactivity (psychology) , combinatorial chemistry , coupling reaction , catalysis , organic chemistry , medicinal chemistry , medicine , alternative medicine , pathology
The effects of β‐hydrogen‐containing alkyl Grignard reagents in simple ferric salt cross‐couplings have been elucidated. The reaction of FeCl 3 with EtMgBr in THF leads to the formation of the cluster species [Fe 8 Et 12 ] 2− , a rare example of a structurally characterized metal complex with bridging ethyl ligands. Analogous reactions in the presence of NMP, a key additive for effective cross‐coupling with simple ferric salts and β‐hydrogen‐containing alkyl nucleophiles, result in the formation of [FeEt 3 ] − . Reactivity studies demonstrate the effectiveness of [FeEt 3 ] − in rapidly and selectively forming the cross‐coupled product upon reaction with electrophiles. The identification of iron‐ate species with EtMgBr analogous to those previously observed with MeMgBr is a critical insight, indicating that analogous iron species can be operative in catalysis for these two classes of alkyl nucleophiles.