The N-Methylpyrrolidone (NMP) Effect in Iron-Catalyzed Cross-Coupling with Simple Ferric Salts and MeMgBr.

Autor: Muñoz SB 3rd; Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627-0216, USA., Daifuku SL; Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627-0216, USA., Sears JD; Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627-0216, USA., Baker TM; Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627-0216, USA., Carpenter SH; Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627-0216, USA., Brennessel WW; Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627-0216, USA., Neidig ML; Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627-0216, USA.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2018 May 28; Vol. 57 (22), pp. 6496-6500. Date of Electronic Publication: 2018 May 08.
DOI: 10.1002/anie.201802087
Abstrakt: The use of N-methylpyrrolidone (NMP) as a co-solvent in ferric salt catalyzed cross-coupling reactions is crucial for achieving the highly selective, preparative scale formation of cross-coupled product in reactions utilizing alkyl Grignard reagents. Despite the critical importance of NMP, the molecular level effect of NMP on in situ formed and reactive iron species that enables effective catalysis remains undefined. Herein, we report the isolation and characterization of a novel trimethyliron(II) ferrate species, [Mg(NMP) 6 ][FeMe 3 ] 2 (1), which forms as the major iron species in situ in reactions of Fe(acac) 3 and MeMgBr under catalytically relevant conditions where NMP is employed as a co-solvent. Importantly, combined GC analysis and 57 Fe Mössbauer spectroscopic studies identified 1 as a highly reactive iron species for the selective formation generating cross-coupled product. These studies demonstrate that NMP does not directly interact with iron as a ligand in catalysis but, alternatively, interacts with the magnesium cations to preferentially stabilize the formation of 1 over [Fe 8 Me 12 ] - cluster generation, which occurs in the absence of NMP.
(© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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