C–H bond halogenation catalyzed or mediated by copper: an overview

Abstract

Carbon-halogen (C-X) bonds are amongst the most fundamental groups in organic synthesis, they are frequently and widely employed in the synthesis of numerous organic products. The generation of a C-X bond, therefore, constitutes an issue of universal interest. Herein, the research advances on the copper-catalyzed and mediated C-X (X = F, Cl, Br, I) bond formation via direct C-H bond transformation is reviewed. 2132

In situ Generation of Hypervalent Iodine Reagents for the Electrophilic Chlorination of Arenes

“…The synthesis of chloroarenes has been a staple in the chemical literature, with processes such as the Sandmeyer reaction, the electrophilic aromatic halogenation, and the stoichiometric ortho ‐metalation/chlorination sequence as some of the most popular approaches. As a complement to these classical methods, metal‐catalyzed chlorination has also received significant attention, with much efforts focused on transition metal catalyzed chelation‐directed aryl C–H ortho activation/chlorination (Ni, Rh, Pd and Ru); and more recently aryl C–H activation/ meta chlorination (Pd)[8d], and aryl C–H activation para chlorination (Fe) . However, the requirement of a directing group results in a somewhat limited substrate scope for these methods.…”

The Influence of Copper on Halogenation/Dehalogenation Reactions of Aromatic Compounds and Its Role in the Destruction of Polyhalogenated Aromatic Contaminants

“…Copper and its salts exhibit broad catalytic activity mainly due to the easily accessible and reasonable stability of Cu(0), Cu(I), Cu(II) and Cu(III) oxidation states. They are therefore effective catalysts not only for C arom -H bonds transformations by single electron transfer (SET) processes [1,2] but through using appropriate conditions even for C aromhalogen cleavage reactions by SET, two-electron transfer, or other mechanisms [3,4]. Copper also ranks among the cheap, earth-abundant first-row transition metals which are more environmentally acceptable (relatively less toxic) metals in comparison with noble platinum group metals, gold or silver.…”

“…It should be noted that traditional methods for halogenation at the heterobenzyl position with NCS, NBS, or NIS result in mixtures of the monohalogenated product and the dihalogenated side product. In recent years, the formation of C-F chemical bonds received global research interest due to the particular functions of many fluorinated chemicals [2]. Accordingly, C-H fluorination reactions also become an issue of broad concern as such a transformation provides a straightforward route for rapid synthesis of diversity-enriched fluorinated products.…”

Metal‐Free Synthesis of Etherified 3‐(1H‐1,2,3‐Triazol‐1‐yl)phenyl Iodides through O–H Arylation/C–H Iodination with Diacetoxyiodobenzenes

“…An aryloxylation process was also achieved by using an Ullmann C–O coupling reaction to generate a series of etherified 1,2,3‐triazoles . For C–H bond halogenations, the Liu group reported a copper‐catalyzed and mediated C–X (X = F, Cl, Br, I) bond formation that proceeded through a direct C–H bond transformation. To the best of our knowledge, however, there has been no report of the metal‐free synthesis of etherified 3‐(1 H ‐1,2,3‐triazol‐1‐yl)phenyl iodides.…”