Work

The Effect of β‐Hydrogen Atoms on Iron Speciation in Cross‐Couplings with Simple Iron Salts and Alkyl Grignard Reagents

Year: 2019

Type: article

Abstract: 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.

Source: Angewandte Chemie International Edition

DOI: 10.1002/anie.201813578