1311295-05-2Relevant articles and documents
Nickel-catalyzed cross-coupling of aryl bromides with tertiary grignard reagents utilizing donor-functionalized N-heterocyclic carbenes (NHCs)
Lohre, Claudia,Droege, Thomas,Wang, Congyang,Glorius, Frank
, p. 6052 - 6055 (2011)
Metal-catalyzed cross-coupling reactions are among the most important transformations in organic synthesis, allowing the efficient construction of complex structures from simpler, readily available building blocks.Many applications in large and small-scale synthesis can be found in different areas such as agrochemicals, pharmaceuticals and supramolecular chemistry. Whereas the coupling of sp2-hybridized carbon atoms in either reaction partner is well established, the use of CACHTUNGTRENUNG(sp3)-hybridized substrates presents some challenges. Catalytic cross-coupling of sterically hindered tertiary alkyl substrates is especially difficult, generally resulting in low yields, and thus, only few reports exist.[27] A big challenge in this field is not only to get the required level of reactivity, but also to overcome competing pathways like β-hydride elimination, hydrodehalogenation or isomerization
Synthesis and characterization of oxygen-functionalised-NHC silver(i) complexes and NHC transmetallation to nickel(ii)
Hameury, Sophie,De Fremont, Pierre,Breuil, Pierre-Alain R.,Olivier-Bourbigou, Helene,Braunstein, Pierre
supporting information, p. 4700 - 4710 (2014/03/21)
The new alcohol- and ether-functionalised-NHC silver(i) complexes bis(1-(2,6-diisopropylphenyl)-3-(2-hydroxyethyl)-1H-imidazol-2(3H)-ylidene) silver(i) chloride, [Ag{ImDiPP(C2OH)}2]Cl (4), bis(1-(2-hydroxyethyl)-3-mesityl-1H-imidazol-2(3H)-ylidene)silver(i) chloride, [Ag{ImMes(C2OH)}2]Cl (5), bis(1-(2-hydroxyethyl)-3-methyl- 1H-imidazol-2(3H)-ylidene)silver(i) chloride, [Ag{ImMe(C2OH)} 2]Cl (6), bis(1-(2,6-diisopropylphenyl)-3-(2-hydroxyethyl)-1H- imidazol-2(3H)-ylidene)silver(i) tetrafluoroborate, [Ag{ImDiPP(C 2OH)}2]BF4 (9), and bis(1-(2,6- diisopropylphenyl)-3-(2-methoxyethyl)-1H-imidazol-2(3H)-ylidene)silver(i) chloride, [Ag{ImDiPP(C2OMe)}2]Cl (13), were synthesized and fully characterized by NMR spectroscopy and single crystal X-ray diffraction. For some complexes, an uncommon heteronuclear coupling 4J(107/109Ag-H) was unveiled. Their ability to transfer the NHC ligand to Ni(ii) was assessed in the presence of different nickel(ii) sources; the bis-NHC Ni(ii) complex bis(1-(2,6-diisopropylphenyl)-3-(2- methoxyethyl)-1H-imidazol-2(3H)-ylidene)nickel(ii) chloride, [NiCl 2{ImDiPP(C2OMe)}2] (15), was obtained from 13 and shown by X-ray diffraction study to have a trans-arrangement of the two NHC ligands. However, in contrast to other Ag(i) NHC complexes the transmetallation reaction failed with the hydroxyl-functionalised silver complexes, possibly due to the acidity of the alcohol OH function, leading overall to reprotonation of the CNHC and isolation of the corresponding imidazolium salts.
