Alkyl Grignard cross-coupling of aryl phosphates catalyzed by new, highly active ionic iron(II) complexes containing a phosphine ligand and an imidazolium cation

作者：Li, Zhuang; Liu, Ling; Sun, Hong-mei^*; Shen, Qi; Zhang, Yong

来源：Dalton Transactions, 2016, 45(44): 17739-17747.

DOI：10.1039/c6dt02995g

• N-HETEROCYCLIC CARBENES
• NITROGEN-CONTAINING HETEROCYCLES
• GENERATED MAGNESIUM AMIDE
• HETEROARYL BORONIC ACIDS
• O BOND ACTIVATION
• ORGANIC-SYNTHESIS
• C-H
• RADICAL POLYMERIZATION
• NICKEL(II) COMPLEXES
• PALLADIUM COMPLEXES

A novel family of ionic iron(II) complexes of the general formula [HL][Fe(PR'(3))X-3] (HL = 1,3-bis(2,6-di-isopropylphenyl) imidazolium cation, HIPr, R' = Ph, X = Cl, 2; HL = HIPr, R' = Cy, X = Cl, 3; HL = HIPr, R' = Ph, X = Br, 4; HL = HIPr, R' = Cy, X = Br, 5; HL = 1,3-bis(2,4,6-trimethylphenyl) imidazolium cation, HIMes, R' = Cy, X = Br, 6) was easily prepared via a stepwise approach in 88%-92% yields. In addition, an ionic iron(II) complex, [HIPr][Fe(C4H8O)Cl-3] (1), has been isolated from the reaction of FeCl2(THF)(1.5) with one equiv. of [HIPr] Cl in 90% yield and it can further react with one equiv. of PPh3 or PCy3, affording the corresponding target iron(II) complex 2 or 3, respectively. All these complexes were characterized by elemental analysis, electrospray ionization mass spectrometry (ESI-MS), H-1 NMR spectroscopy and X-ray crystallography. These air-insensitive complexes 2-6 showed high catalytic activities in the cross-coupling of aryl phosphates with primary and secondary alkyl Grignard reagents with a broad substrate scope, wherein [HIPr][Fe(PCy3)Br-3] (5) was the most effective. Complex 5 also catalyzes the reductive cross-coupling of aryl phosphates with unactivated alkyl bromides in the presence of magnesium turnings and LiCl, as well as the corresponding one-pot acylation/cross-coupling sequence under mild conditions.

• 出版日期2016
• 单位苏州大学