Beilstein J. Org. Chem.2021,17, 2488–2495, doi:10.3762/bjoc.17.165
the directing group could be removed easily under basic conditions.
Keywords: amination; C–H activation; copper; ferrocene; mono-selectivity; Introduction
Ferrocene-based compounds have broad applications from asymmetric catalysis to medicinal discovery [1][2][3][4][5][6][7][8]. Therefore, the
groups. Kumar and co-workers developed a Cu-mediated C–H chalcogenation and sulfonation of ferrocenes [27][28][29]. The use of a bidentate 1,10-phenathroline ligand was critical to achieve mono-selectivity in the chacogenation reactions [28]. Meanwhile, Co(III)-catalyzed ortho-C–H amidation of ferrocene
excellent mono-selectivity and no diaminated ferrocenylamide was detected. The exclusive monoselectivity is most likely originated from the strong coordination of the amino group, which could form a tridentate copper complex and prevent the second C–H amination [34][50].
Having obtained the optimized
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Graphical Abstract
Scheme 1:
3d-Transition-metal-catalyzed C–H functionalization to access functionalized ferrocenes.
Beilstein J. Org. Chem.2016,12, 1243–1249, doi:10.3762/bjoc.12.119
provided PA-coupled THQ products in good yields.
Although ε-C−H iodination via directed SEAr proceeds with excellent yield and mono-selectivity for many γ-arylpropylpicolinamides, the scope of these PA-directed SEAr reactions is limited to arenes bearing moderate electron-donating or withdrawing groups
Information File 1 for details). The substrate scope was chosen to complement the SEAr method, which is notably incompatible with NO2, F and OMe substituents. In contrast to the mono-selectivity of the directed SEAr approach (reaction 2, Scheme 1), iodination of γ-phenylpropylpicolinamide 2 bearing two
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Graphical Abstract
Scheme 1:
New synthetic strategy for THQs via PA-directed C−H functionalization.