Halogenase-mimicking selective chlorination of unactivated C-H bonds by a Fe-complex
Himangshu Kuiry1, Anish Gangopadhyay1, Bittu Chandra1
1Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India. sayam.sengupta@iiserkol.ac.in.
None:
In this study, we report a selective aliphatic C-H bond chlorination mediated by Fe-bTAML (bTAML: biuret-modified tetraamido macrocyclic ligand) using sodium hypochlorite as the chlorine source. The reaction predominantly yields chlorinated products over hydroxylated ones across various unactivated C-H bonds in acetonitrile-water medium. The formation of rearranged chlorinated products in norcarane and the absence of stereo-retention in cis-dimethylcyclohexane suggests the involvement of a long-lived, cage-escaped carbon radical intermediate. UV-Vis and EPR spectroscopic analyses confirm the presence of [FeV(O)-(NO2)bTAML]- (2) as the reactive intermediate. The 3°:2° selectivity in hydrocarbons, kinetic isotope effect (KIE), and detailed kinetic studies indicate hydrogen atom abstraction (HAA) by [FeV(O)-(NO2)bTAML]- (2) as the rate-determining step.
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