Direct C–H bond halogenation and pseudohalogenation of hydrocarbons mediated by high-valent 3d metal-oxo species

Abstract

Late-stage direct functionalization of C–H bond is synthetically desirable. Metalloenzymes having metal-oxo active sites are well known to selectively catalyze hydroxylation and halogenation reactions with high efficiency. This review highlights...

C–H bond chlorination using nickel(ii) complexes of tetradentate amido-quinoline ligands

“…Inspired by the reactivity of these metalloenzymes towards the activation of inert C–H bonds, immense research has been carried out towards the development of synthetic biomimetic catalysts and their reactivity towards alkane halogenation. 5 Manganese porphyrin complexes reported by Groves and co-workers served as an excellent catalyst for the effective chlorination of alkanes. 6 Beside this, iron complexes were also used to catalyse the halogenation reactions.…”

“…11 To date, despite several synthetic catalysts developed using first row transition metals, a major concern is the formation of unwanted hydroxylated products during the synthesis of the halogenated product (Scheme 1). 5,8 Thus the opportunity is there for synthetic chemists to develop a new protocol for selective halogenation employing synthetic catalysts. Herein, we report Ni( ii ) complexes supported by amido-quinoline ligands, which can effectively catalyse C–H chlorination of strong C–H bonds giving exclusively chlorinated products without any hydroxylated products.…”

Directing transition metal-based oxygen-functionalization catalysis

“…1c. 53 Lastly, high-valent Ru-oxo species, such as Ru IV ]O, Ru V ] O, and Ru VI ]O, have emerged as reactive species for water oxidation, epoxidation, and C-H oxidation. 54 Ruthenium imine complexes, like Ru(bpy) 2 Cl 2 (bpy ¼ 2,2 0 -bipyridine), are among the most distinguished ruthenium complexes oxidized to generate the Ru IV ]O intermediate.…”

Recent Advances in First‐Row Transition‐Metal‐Mediated C−H Halogenation of (Hetero)arenes and Alkanes

“…Thereafter, this radical undergoes halogen atom transfer either from in-situ generated metal-halide complex or metal-hypohalite complex to afford the halogenated product. [17][18][19] Interestingly, most of the halogenating enzymes possesses firstrow transition metals, especially iron and vanadium at their active site. [20] Most importantly, the unique protein architecture in the halogenase enzymes provides a particular arrangement for the positioning of the substrate that favours the regio-as well as stereo-selective halogen transfer.…”

“…[20] Most importantly, the unique protein architecture in the halogenase enzymes provides a particular arrangement for the positioning of the substrate that favours the regio-as well as stereo-selective halogen transfer. [17][18][19]21,22] Additionally, the nucleophilicity, electronegativity and the size of the binding halide contributes significantly towards the observed selectivity. The high regio-and stereo-selectivity of enzyme-catalysis inspired the researchers to emulate the strategies in synthetic chemistry to achieve similar selectivity.…”