Nucleophilic aromatic substitution for hydrogen

Nucleophilic Aromatic Substitution For Hydrogen Oxidation of a-Complex Intermediates... 

Figure 11. Amination of nitrobenzene via nucleophilic aromatic substitution for hydrogen.

Figure 2. Nucleophilic aromatic substitution for hydrogen reaction.

The formation of substituted anilides from the reaction of amides with nitrobenzene is the first example of the direct formation of aromatic amide bonds via nucleophilic aromatic substitution for hydrogen. This reaction proceeds in high yield and regioselectivity, and does not require the use of halogenated materials or auxiliary leaving groups. Furthermore, these studies have demonstrated that the use of O2 as the terminal oxidant in NASH reactions can result in a highly selective and environmentally favorable route for the production of PNA and PPD. 

Two examples of nucleophilic aromatic substitution for hydrogen reactions were described from which we have proposed two new atomically efficient processes for the manufacturing of commercially relevant aromatic amines. Our mechanistic studies have revealed that the direct oxidation of a-complex intermediates by either nitro groups or O2 can eliminate the need for chlorination of benzene as a starting point for the manufacturing of aromatic amines. Accordingly, these reactions demonstrate the key objective of alternate chemical design which is not to make the waste in the first place. 

Elimination of Chlorine in the Synthesis of 4-Aminodiphenylamine A New Process That Utilizes Nucleophilic Aromatic Substitution for Hydrogen... 

One example of feedstock replacement that has been applied commercially is the work of Stem and co-workers (19-21) at the Monsanto Corporation in the synthesis of a variety of aromatic amines. By using nucleophilic aromatic substitution for hydrogen. Stem was able to obviate the need for the use of a chlorinated aromatic in the synthetic pathway. Certain chlorinated aromatics are known to be persistent bioaccumulators and to possess other environmental concerns this research in feedstock replacement resulted in the removal of that concern. 

The regioselective functionalization of nitrobenzene and benzonitrile derivatives has been performed via nucleophilic aromatic substitution of hydrogen by phosphorus-stabilized carbanions.41 Lithium phosphazenes have been found to be the most suitable nucleophiles for the substitution of hydrogen in nitrobenzene. This method represents a convenient alternative to the vicarious nucleophilic substitution for the synthesis of benzylic phosphorus derivatives using phosphorus-stabilized anions that do not bear a leaving group at the carbanionic centre. 

Nucleophilic Aromatic Substitution of Hydrogen as a Tool for Heterocyclic Ring Annulation... 

A.V. Gulevskaya and A.F. Pozharskii (Rostov State University, Russia) write on nucleophilic aromatic substitution of hydrogen, concentrated on the use of this reaction for heterocyclic ring annulation. It covers particularly the recent extension of the general SnH reaction to effect ring annulation. 

Prof V. Charushin is author of over 380 publications in the fields of heterocyclic and medicinal chemistry, including the hoo Nucleophilic Aromatic Substitution of Hydrogen, (Academic Press, New York, 1994), several chapters in Advances in Heterocyclic Chemistry and Progress in NMR Spectroscopy, over 20 review articles, and a lot of papers in international journals. He is a member of the editorial boards for Mendeleev Communications, Russian Chemical Reviews, Russian Chemical Bulletin, and Russian Journal of Organic Chemistry. 

The [AE, (addition-elimination)] and [AO, (addition-oxidation)] reactions of 5-bromopyrimidine with pyrroles and indoles for the synthesis of 4-(lR-pyr-rol-2-yl)-and 4-(lR-indol-3-yl)-5-(hetero)aryl-substituted pyrimidines by combination of the Suzuki-Miyaura cross-coupling and nucleophilic aromatic substitution of hydrogen reactions was carried out by Verbitskiy et al. (2012a). 

Nakamura, Takagi and Ueno have also utilized 4 -nitrobenzo-l 5-crown-5 as a starting material Their goal was the formation of a colored crown which could be utilized in transport studies. They have prepared 4 -picrylaminobenzo-l 5-crown-5 for this purpose in the following way. 4 -Nitrobenzo-l 5-crown-5 was hydrogenated and then picryl chloride was added. Nucleophilic aromatic substitution apparently ensued (deep red color) and the product was th n isolated by standard techniques as a yellow solid (mp 155°, max 395 nm) in 72% yield as shown in Eq. (3.17). 

Amination of aromatic nitro compounds is a very important process in both industry and laboratory. A simple synthesis of 4-aminodiphenyl amine (4-ADPA) has been achieved by utilizing a nucleophilic aromatic substitution. 4-ADPA is a key intermediate in the rubber chemical family of antioxidants. By means of a nucleophibc attack of the anilide anion on a nitrobenzene, a o-complex is formed first, which is then converted into 4-nitrosodiphenylamine and 4-nitrodiphenylamine by intra- and intermolecular oxidation. Catalytic hydrogenation finally affords 4-ADPA. Azobenzene, which is formed as a by-product, can be hydrogenated to aniline and thus recycled into the process. Switching this new atom-economy route allows for a dramatic reduction of chemical waste (Scheme 9.9).73 The United States Environmental Protection Agency gave the Green Chemistry Award for this process in 1998.74... 

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