Cu(ClO₄)₂-Mediated Arene C–H Bond Halogenations of Azacalixaromatics Using Alkali Metal Halides as Halogen Sources

Abstract

Regiospecific halogenation of azacalix[1]arene[3]pyridines at the lower rim position of the benzene ring was achieved from their cross-coupling reaction with cost-effective alkali metal halides through the Cu(ClO(4))(2)-mediated aerobic aryl C-H activation, which gave structurally well-defined aryl-Cu(III) intermediates, and a subsequent C-X bond formation reaction under very mild conditions.

Cu-Catalyzed Direct Amidation of Aromatic C–H Bonds: An Access to Arylamines

“…The coordination of pyrimidyl group in the substrate 1a to the copper(II) center is followed by the disproportionative C–H activation reaction with another Cu(II) species that produces the aryl-Cu(III) intermediate 8 and a Cu(I) species. 17 Subsequently, phthalimide coordinates to the aryl-Cu(III) center and the reductive elimination of Cu(III) intermediate 9 takes place to provide the corresponding aminated product 3a and a Cu(I) species, which would be oxidized by O 2 under acidic conditions to regenerate the Cu(II) species and water as a byproduct. Nevertheless, at present, we cannot completely exclude a single electron transfer (SET) pathway as proposed by Yu et al 13a …”

Copper‐Catalyzed Aromatic CH Bond Cyanation by CCN Bond Cleavage of Inert Acetonitrile

“…Although the detailed mechanism remained unclear at the current stage, a tentative reaction mechanism is proposed on the basis of the mechanistic studies described above and previous findings, [12,20] Finally, the Cu I species is oxidized by oxygen to regenerate the Cu II species, which may be the resting state of the catalyst. [21]…”

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

“…A stoichiometric variation to this chemistry utilizing an all pyridine-based macrocycle was reported by Wang in 2012. 214 This method allowed the fluorination, chlorination, bromination, and iodination of so-called azacalixaromatics and was rendered catalytic in 2014. 215 In 2010 Wu and Hynes reported the Cu(I)-catalyzed conversion of arylboronic acids to aryl chlorides using NCS (Scheme 97).…”