TY - JOUR
T1 - Bis(dialkylphosphino)ferrocene-Ligated Nickel(II) Precatalysts for Suzuki-Miyaura Reactions of Aryl Carbonates
AU - Barth, Emily L.
AU - Davis, Ryan M.
AU - Mohadjer Beromi, Megan
AU - Walden, Andrew G.
AU - Balcells, David
AU - Brudvig, Gary W.
AU - Dardir, Amira H.
AU - Hazari, Nilay
AU - Lant, Hannah M.C.
AU - Mercado, Brandon Q.
AU - Peczak, Ian L.
N1 - Funding Information:
N.H. acknowledges support from the NIHGMS under Award Number R01GM120162. R.M.D. and M.M.B. thank the NSF for support as NSF Graduate Research Fellows. The EPR spectroscopy work was supported by the Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, grant DE-FG02-05ER15646 (G.W.B. and H.M.C.L.). N.H. is a Camille and Henry-Dreyfus Foundation Teacher Scholar. D.B. acknowledges support from the Research Council of Norway through the Hylleraas Centre for Quantum Molecular Sciences (project number 262695). We thank Dr. Fabian Menges for assistance with mass spectrometry.
PY - 2019/9/9
Y1 - 2019/9/9
N2 - Aryl carbonates, a common protecting group in synthetic organic chemistry, are potentially valuable electrophiles in cross-coupling reactions. Here, after performing a thorough evaluation of different precatalysts, we demonstrate that (dcypf)Ni(2-ethylphenyl)(Br) (dcypf = 1,1-bis(dicyclohexylphosphino)ferrocene) is an efficient precatalyst for Suzuki-Miyaura reactions using a variety of aryl carbonates as substrates. Mechanistic studies indicate that (dcypf)Ni(2-ethylphenyl)(Br), which contains a bidentate phosphine that binds in a trans geometry, is an effective precatalyst for these reactions for two reasons: (i) it rapidly forms the Ni(0) active species and (ii) it minimizes comproportionation reactions between the Ni(0) active species and both the unactivated Ni(II) precatalyst and on-cycle Ni(II) complexes to form catalytically inactive Ni(I) species. In contrast, the state of the art precatalyst (dppf)Ni(o-tolyl)(Cl) (dppf = 1,1-bis(diphenylphosphino)ferrocene), which contains a bidentate phosphine that binds in a cis geometry, forms Ni(I) species during activation and is essentially inactive for aryl carbonate couplings. Although the exact reasons on a molecular level why the dcypf system is more active than the dppf system are unclear, our results indicate that in general Ni catalysts supported by the dcypf ligand will give better performance for catalytic reactions involving substrates which undergo relatively slow oxidative addition, such as aryl carbonates.
AB - Aryl carbonates, a common protecting group in synthetic organic chemistry, are potentially valuable electrophiles in cross-coupling reactions. Here, after performing a thorough evaluation of different precatalysts, we demonstrate that (dcypf)Ni(2-ethylphenyl)(Br) (dcypf = 1,1-bis(dicyclohexylphosphino)ferrocene) is an efficient precatalyst for Suzuki-Miyaura reactions using a variety of aryl carbonates as substrates. Mechanistic studies indicate that (dcypf)Ni(2-ethylphenyl)(Br), which contains a bidentate phosphine that binds in a trans geometry, is an effective precatalyst for these reactions for two reasons: (i) it rapidly forms the Ni(0) active species and (ii) it minimizes comproportionation reactions between the Ni(0) active species and both the unactivated Ni(II) precatalyst and on-cycle Ni(II) complexes to form catalytically inactive Ni(I) species. In contrast, the state of the art precatalyst (dppf)Ni(o-tolyl)(Cl) (dppf = 1,1-bis(diphenylphosphino)ferrocene), which contains a bidentate phosphine that binds in a cis geometry, forms Ni(I) species during activation and is essentially inactive for aryl carbonate couplings. Although the exact reasons on a molecular level why the dcypf system is more active than the dppf system are unclear, our results indicate that in general Ni catalysts supported by the dcypf ligand will give better performance for catalytic reactions involving substrates which undergo relatively slow oxidative addition, such as aryl carbonates.
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U2 - 10.1021/acs.organomet.9b00543
DO - 10.1021/acs.organomet.9b00543
M3 - Article
AN - SCOPUS:85072330344
VL - 38
SP - 3377
EP - 3387
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 17
ER -