123594-82-1Relevant articles and documents
Mixed Alkyl/Aryl Diphos Ligands for Iron-Catalyzed Negishi and Kumada Cross Coupling Towards the Synthesis of Diarylmethane
Ma, Xufeng,Wang, Han,Liu, Yao,Zhao, Xing,Zhang, Jun
, p. 5134 - 5140 (2021/11/16)
Mixed alkyl/aryl diphos ligands have been prepared and their application in iron-catalyzed cross coupling of benzylic chlorides with diaryl zinc (Negishi) or aryl Grignard reagents (Kumada) towards the synthesis of diarylmethane has been evaluated. The iron?diphos catalytic system exhibited the enhanced activity and selectivity in the two coupling reactions. The electron-rich mixed PPh2/PCy2 ligands outperformed their symmetrical PPh2 congeners, and led to decreased homocoupling byproduct formation. It indicates that the electronic effect of the ligands plays an important role in the catalytic performance. The Fe catalyst supported by L8 bearing an electron-rich PCy2 substituent and a sterically demanding tert-butyl on ethene backbone exhibited the best catalytic performance and good functional group tolerance in the two cross coupling reactions.
Subtle effects of ligand backbone on the efficiency of iron-diphos catalysed Negishi cross-coupling reactions
Clifton, Jamie,Habraken, Evi R. M.,Pringle, Paul G.,Manners, Ian
, p. 4350 - 4353 (2015/09/01)
Substantially more active iron catalysts for a standard Negishi cross-coupling are obtained when bis(diarylphosphino)thiophenes are employed in place of the benchmark ligand bis(diphenylphosphino)benzene. The thiophene ligands have the advantages of ease of synthesis and ready modification.
Iron phosphine catalyzed cross-coupling of tetraorganoborates and related group 13 nucleophiles with alkyl halides
Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Clifton, Jamie,Cogswell, Paul M.,Gower, Nicholas J.,Haddow, Mairi F.,Harvey, Jeremy N.,Kehl, Jeffrey A.,Murphy, Damien M.,Neeve, Emily C.,Neidig, Michael L.,Nunn, Joshua,Snyder, Benjamin E. R.,Taylor, Joseph
, p. 5767 - 5780 (2015/02/19)
Iron phosphine complexes prove to be good precatalysts for the cross-coupling of alkyl, benzyl, and allyl halides with not only aryl triorganoborate salts but also related aluminum-, gallium-, indium-, and thallium-based nucleophiles. Mechanistic studies revealed that while Fe(I) can be accessed on catalytically relevant time scales, lower average oxidation states are not formed fast enough to be relevant to catalysis. EPR spectroscopic studies reveal the presence of bis(diphosphine)iron(I) complexes in representative catalytic reactions and related processes with a range of group 13 nucleophiles. Isolated examples were studied by M?ssbauer spectroscopy and single-crystal X-ray structural analysis, while the electronic structure was probed by dispersion-corrected B3LYP DFT calculations. An EPR study on an iron system with a bulky diphosphine ligand revealed the presence of an S = 1/2 species consistent with the formation of a mono(diphosphine)iron(I) species with inequivalent phosphine donor environments. DFT analysis of model complexes allowed us to rule out a T-shaped Fe(I) structure, as this is predicted to be high spin.
