Recent advances in copper-mediated chelation-assisted functionalization of unactivated C–H bonds

Abstract

Transition metal-catalyzed direct functionalization of C-H bonds has recently emerged as a powerful strategy for the construction of carbon-carbon and carbon-heteroatom bonds. Among various metals employed, base metal copper has attracted significant attention owing to its relatively low cost, abundance, and versatile reactivity. This review aims to comprehensively summarize the recent advances in copper-mediated (both stoichiometric and catalytic) chelation-assisted functionalization of unactivated C-H bonds.Scheme 1 Copper-mediated cross-coupling and C-H functionalization.

Synthesis and Characterization of a Binuclear Copper(II)-dipyriamethyrin Complex: [Cu2(dipyriamethyrin)(μ2-1,1-acetato)2]

“…Formation of the initial mono-metallated complex is postulated to arise through cooperation between the Cu(II) cation and acetate counter by a concerted metalation-deprotonation (CMD)-type mechanism (cf. ESI, Scheme 1) [61][62][63]. Crystals suitable for X-ray diffraction analysis were grown via evaporation of a dichloromethane: hexanes (1:2, v/v) solution of 2.…”

Cu(II)‐Mediated C−C/C−O Bond Formation via C−H/C−C Bond Cleavage: Access to Benzofurans Using Amide as a Traceless Directing Group

“…More recently, the combination of copper salts with N,N-bidentate directing groups has provided a promising tool for the formation of carbon-carbon and carbon-hetero bonds. [11] A series of novel direct couplings with the assistance of bidentate auxiliaries in the presence of copper catalysts have been developed. [12] However, copper-catalyzed or -mediated cascade coupling reactions involving multiple bond breakings and reformations in a one-pot operation to furnish various heterocycles remains quite limited.…”

“…Disappointingly, replacement of DMSO with other solvents, including DMF, NMP, DMPU and MeCN, was not beneficial to this transformation (Table 1, entries 7-10). No improvement was acquired when other Cu salts or other metal catalysts were used (Table 1, entries[11][12][13][14][15][16][17]. The product was not detected in the absence of copper salt(Table 1, entry 18).…”

Ni‐Catalyzed Chelation‐AssistedDirect Functionalization of Inert C—H Bonds

“…When adapted as catalysts, novel reactivity could generally be discovered. [8] Therefore, while the second or third-row transition metals (e.g., Pd, Rh, Ir, Ru) keep leading the field of inert C-H bond activation, the more sustainable variants mediated by the first row transition metals (e.g., Fe, [9] Co, [10] Ni, [11] Cu [12] ) have witnessed a marked progress. In this regard, Ni-catalyzed reactions have received significant attention, owing to the high catalyst flexibility and chemical versatility caused by wide oxidation state of nickel element (from Ni(0), Ni(I), Ni(II), Ni(III) to Ni(IV)).…”