Oxidative nucleophilic aromatic amination of nitrobenzenes

Para-selective nitrobenzene amination lead by C(sp2)-H/N-H oxidative cross-coupling through aminyl radical

Arylamines, serving as crucial building blocks in natural products and finding applications in multifunctional materials, are synthesized on a large scale via an electrophilic nitration/reduction sequence. However, the current methods for aromatic C-H amination have not yet attained the same level of versatility as electrophilic nitration. Here we show an extensively investigated transition metal-free and regioselective strategy for the amination of nitrobenzenes, enabling the synthesis of 4-nitro-N-arylamines through C(sp2)-H/N-H cross-coupling between electron-deficient nitroarenes and amines. Mechanistic studies have elucidated that the crucial aspects of these reactions encompass the generation of nitrogen radicals and recombination of nitrobenzene complex radicals. The C(sp2)-N bond formation is demonstrated to be highly effective for primary and secondary arylamines as well as aliphatic amines under mild conditions, exhibiting exceptional tolerance towards diverse functional groups in both nitroarenes and amines (>100 examples with yields up to 96%). Notably, this C(sp2)-H/N-H cross-coupling exhibits exclusive para-selectivity.

Amination of Nitro-Substituted Heteroarenes by Nucleophilic Substitution of Hydrogen

An open-air method for the transition metal-free direct amination of nitro(hetero)arenes by anilines is disclosed. In this methodology, an aromatic C-H bond is substituted via oxidative nucleophilic aromatic substitution of hydrogen (ONSH). Density functional theory calculations and mechanistic studies support a dianion pathway with oxidation by molecular oxygen as the rate-limiting step.

Oxidative nucleophilic alkoxylation of nitrobenzenes

Oxidative nucleophilic aromatic substitution of hydrogen in nitroaromatics with potassium alkoxides is reported.

Electrophilic and Nucleophilic Aromatic Substitutions are Mechanistically Similar with Opposite Polarity

Confrontation of the recently formulated general mechanism of nucleophilic substitution in electron-deficient arenes with the well-known mechanism of electrophilic substitution revealed that these fundamental processes are mechanistically identical but proceed according to opposite polarity-an Umpolung relation. In this viewpoint this apparently controversial concept is supported by discussion of a variety of experimental results.

Direct synthesis of nitroaryl acetylenes from acetylenes and nitroarenes via oxidative nucleophilic substitution of hydrogen

Acetylenic carbanions add to nitroarenes (dinitrobenzenes, nitropyridines, etc.) to form σ^H-adducts that are subsequently oxidized by DDQ according to the oxidative nucleophilic substitution of hydrogen (ONSH) pathway to give nitroaryl acetylenes.

Green and practical transition metal-free one-pot conversion of substituted benzoic acids to anilines using tosyl azide

A simple and efficient method for conversion of 2-iodo/2-nitro benzoic acids and dihydropyranone-fused benzoic acids into corresponding anilines, using tosyl azide, under transition metal-free conditions was developed. Steric and electronic effects play crucial role.