Transition-Metal-Free Electrophilic Amination of Arylboroxines

Abstract

A transition-metal-free strategy to construct C(sp(2))-N bonds using arylboroxines and O-benzoyl hydroxylamines as coupling partners has been developed. This transformation provides a useful method to access various aromatic amines.

Transition Metal‐Free ipso‐Functionalization of Arylboronic Acids and Derivatives

“…[27] O -Benzoyl hydroxylamine was employed as aminating reagent. A number of tertiary anilines, as well as a few secondary anilines, were readily generated at 130 °C (Scheme 13).…”

Cobalt‐Catalyzed Electrophilic Amination of Arylzincs with N‐Chloroamines

“…[1] Over the past decade, the Buchwald-Hartwig amination of electrophilic aromatics involving Pd, [2] Cu, [3] and Ni [4] centers has become a prominent and elegant method for creating C À N bonds and forming functionalized arylamines. These umpolung procedures have been reported with stoichiometric Ti, [7] catalytic Ni [8] or Cu [9] , and even transition-metal free [10] catalytic systems. [5] However, all these reactions require sophisticated and expensive ligands.…”

“…More recently, catalytic systems based on cobalt have also been reported. These umpolung procedures have been reported with stoichiometric Ti, [7] catalytic Ni [8] or Cu [9] , and even transition-metal free [10] catalytic systems. Moreover, stoichiometric amounts of base or high reaction temperatures (usually around 100 8C) are often necessary to achieve the reactions.…”

Intermolecular versus Intramolecular Palladium‐Catalyzed Direct Arylations between 1‐(2‐Bromobenzyl)imidazoles and Aryl Bromides

“…This is aknown compound and the spectral data are identical to those reportedinl iterature. [25] 4-[1-(2-Bromobenzyl)-2-methylimidazol-5-yl]benzonitrile (18): Followingt he procedure A using 1-(2-bromobenzyl)-2-methyl-1H-imidazole (377 mg, 1.5 mmol) and 4-bromobenzonitrile (218 mg, 1mmol), the residuew as purifiedb yf lash chromatography on silica gel (pentane-Et 2 O, 90:10) to afford the desired compound 18;y ield:2 14 mg (61%). (21): Following the procedure B using 1-(2-bromobenzyl)-2-methyl-5-(4-nitrophenyl)imidazole (20)( 150 mg, 0.40 mmol), the residue was purified by flash chromatography on silica gel (pentane) to afford the desired compound 21;y ield:7 3mg( 63%).…”