Substitution Of Hydrogen In Nitroarenes Research Articles

The Coupling of Carbon and Nitrogen Substituents with Nitroarenes: Vicarious Nucleophilic Substitution of Hydrogen in Nitroarenes

Abstract: In recent years, nitroarenes have been extensively exploited as green, efficient electrophilic arylation reagents used in a variety of organic syntheses. Transition-metal-free cross-coupling reactions and vicarious nucleophilic substitution (VNS) have become practical and reliable synthetic methods to access momentous functionalized organic compounds. Thus, the introduction of various substituents into nitroarenes has attracted considerable attention as important synthetic approaches due to their simplicity and practicality. In this review, we comprehensively summarize the coupling of several carbon and nitrogen substituents with nitroarenes via nucleophilic substitution under mild conditions, followed by the application of these transversions in the construction of carbon and heterocyclic rings.

Introduction of Carbon Substituents into Nitroarenes via Nucleophilic Substitution of Hydrogen: New Developments

Nucleophilic substitution of hydrogen in nitroarenes has become a powerful synthetic tool for functionalization of these important organic substrates, complementary to other modern methods. In this review we present new developments in the area of introduction of alkyl and functionalized alkyl substituents into nitroarene rings via nucleo­philic substitution of hydrogen, followed by application of these processes in the construction of carbo- and heterocyclic rings. Finally, new developments in the investigation of the mechanism of SNArH are summarized.1 Introduction2 Alkylation and Haloalkylation3 Functionalized Carbon Substituents4 Formation of Carbo- and Heterocyclic Rings5 Mechanistic Aspects of SNArH6 Conclusion

A two-step oxidative aromatic substitution of hydrogen as a convenient way to 2-nitrodiarylamines

A method for the synthesis of differently substituted 2-nitrodiarylamines via nucleophilic substitution of hydrogen in nitroarenes is described. In the two-step procedure, the first step omits classical substitution of halogens in starting nitroarenes and occurs efficiently at the position ortho to the activating group. Subsequent oxidation of the 2-nitrosoanilines so formed is accomplished with a cheap and environmentally friendly reagent, sodium perborate, under mild conditions. In exceptional cases of the amine-substituted nitrosoanilines, more selective oxidant (IBX) is required.

ChemInform Abstract: Application of Nucleophilic Substitution of Hydrogen in Nitroarenes to the Chemistry of Indoles

AbstractReview: 108 refs.

Application of nucleophilic substitution of hydrogen in nitroarenes to the chemistry of indoles

Application of nucleophilic substitution of hydrogen in nitroarenes to the synthesis and transformation of indoles is discussed.

Synthesis of Heterocycles via Nucleophilic Substitution of Hydrogen in Nitroarenes

Synthesis of Heterocycles via Nucleophilic Substitution of Hydrogen in Nitroarenes

Reactions of oxidative nucleophilic substitution of hydrogen in nitroarenes

The review summarizes information on the reactions of oxidative nucleophilic substitution of hydrogen in nitro derivatives of carboaromatic substrates with N-, C-, O-, and P-nucleophiles.

Nucleophilic Substitution of Hydrogen in Nitroarenes: A New Chapter of Aromatic Chemistry

Basic concepts, mechanistic principles and the broad application of nucleophilic substitution of hydrogen in nitroarenes and other electron-deficient arenes in organic synthesis are presented in a concise way. It was shown that the initial process between nucleophiles and (halo)nitroarenes is a fast and reversible addition - in positions occupied by hydrogen - to form anionic σH adducts that can then be converted into products of nucleophilic substitution of hydrogen in a few ways. Only when these pathways for rapid conversion of the σH adducts into products of nucleophilic substitution of hydrogen are not available, do the σH adducts dissociate. The subsequent slower formation of σX adducts, followed by departure of X anions, results in the conventional nucleophilic aromatic sub­stitution of halogens, namely the SNAr reaction. Thus the SNAr reaction is a secondary ipso substitution, whereas nucleophilic substitution of hydrogen is a primary fast process. It is therefore necessary to introduce corrections in appropriate chapters of textbooks and monographs.

Synthesis of nitroaryl derivatives of glycine via oxidative nucleophilic substitution of hydrogen in nitroarenes

Carbanion of ethyl N-(1,3-dithiolan-2-ylidene)glycinate adds to activated nitroarenes mostly in para position to the nitro group. Subsequent oxidation of the resulting σ adducts with DDQ gave respective α-nitroarylated glycine derivatives in moderate yields. The reaction of esters of chiral alcohols such as (-)-menthol or (-)-8-phenylmenthol proceeds with a moderate or high diastereoselectivity leading to enantiomerically enriched nitroarylglycines.

Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes with Carbanions of Protected Serine and Threonine Esters

AbstractThe reactions of carbanions of protected serine and threonine esters with nitroarenes were studied. The main process involves the addition of the carbanions to the para position of the nitroarenes, which is occupied by a hydrogen atom, to form σH adducts that are subsequently oxidized by 2,3‐dichloro‐5,6‐dicyanobenzoquinone to give p‐nitroaryl derivatives of the protected serine and threonine. Oxidation of the σH adducts with dimethyldioxirane resulted in the formation of the corresponding p‐hydroxyaryl derivatives of these amino acids. Addition of the carbanions of the protected threonine ester is a highly stereoselective process controlled by the second chiral center of threonine.

ChemInform Abstract: Synthesis of 2,1‐Benzisoxazoles by Nucleophilic Substitution of Hydrogen in Nitroarenes Activated by the Azole Ring.

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Synthesis of 2,1-Benzisoxazoles by Nucleophilic Substitution of Hydrogen in Nitroarenes Activated by the Azole Ring

Reaction of 1-nitro-4-(1,2,3-triazolyl/tetrazolyl)benzenes with arylacetonitriles in an alcoholic medium in the presence of excess alkali gives novel 2,1-benzisoxazoles. These findings indicate a high reactivity of nitroarenes activated by the azole ring due to their electron-deficient character. Moreover, it was found that annulation of the isoxazole ring occurred regioselectively in disubstituted nitroarenes. In the case of 1-(4-nitrophenyl)-1H-tetrazole, the tetrazole ring cleaved faster than the σ H -adduct was formed.

Synthesis of α-(Nitroaryl)benzylphosphonates via Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes

Carbanions of diethyl benzylphosphonate and diethyl 1-phenylethylphosphonate add to nitroarenes to form relatively long-lived sigma(H) adducts that can be oxidized to products of oxidative nucleophilic substitution of hydrogen. By variation of the conditions, o- and p-nitroarylated derivatives of the starting phosphonates can be synthesized regioselectively. It has been proven that addition of carbanions of diethyl benzylphosphonate and diethyl 1-phenylethylphosphonate to nitroarenes is a fast process and the respective sigma(H) adducts are formed almost quantitatively.

Synthesis of Diphenyl(nitroaryl)phosphine Oxides via Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes with Diphenylphosphine Anion

Potassium and sodium salts of diphenylphosphine add to nitroarenes in the position ortho and para to the nitro group. Subsequent oxidation of σ H -adducts with potassium permanganate gave diphenyl(nitroaryl)phosphine oxides.

Enantioselective Synthesis of (R)-α-(p-Nitroaryl)prolines via Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes

Optically pure ( R)-α-( P-nitroaryl)prolines are synthesized via oxidative nucleophilic substitution of hydrogen in nitroarenes using chiral carbanion of L-proline protected as N, O-acetal of pivalaldehyde.

Simple and General Synthesis of α-(p-Nitroaryl) Derivatives of Alanine and Serine

α-(p-Nitroaryl)alanine and a-(p-nitroaryl)serine alkyl esters are efficiently synthesized via oxidative nucleophilic substitution of hydrogen in nitroarenes with carbanions of protected alanine and serine.

Oxidative nucleophilic substitution of hydrogen in nitroarenes with an oxazoline stabilised carbanion

The carbanion of 4,4-dimethyl-2-(1-phenylethyl)-4,5-dihydro-1,3-oxazole adds 1 to nitroarenes in the position para to the nitro group: oxidation of the produced σ H adducts with dichlorodicyanobenzoquinone (DDQ) gives para-substituted nitroarenes whereas oxidation with dimethyldioxirane (DMD) leads to para- substituted phenols.

Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes with Phenylacetic Acid Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Oxidative nucleophilic substitution of hydrogen in nitroarenes with phenylacetic acid derivatives

Oxidative nucleophilic substitution of hydrogen (ONSH) in nitroarenes with carbanion of isopropyl phenyl acetate gives various products depending on the conditions and oxidant. The reaction carried out in liquid ammonia and KMnO 4 oxidant gives iso-propyl α-hydroxy-α-nitroarylphenylacetates formed via hydroxylation of the initial ONSH products. In some cases additionally dimeric, trimeric and tetrameric products are formed. In THF and Bu 4N +MnO 4 − or DDQ oxidants simple ONSH products are formed whereas oxidation by dimethyl dioxirane (DMD) gave iso-propyl hydroxyaryl phenyl acetates. The dimeric and trimeric products are apparently formed via coupling of nitrobenzylic radicals generated in course of oxidation with nitrobenzylic carbanions of the ONSH products.

Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes with Trifluoromethyl Carbanions. Synthesis of Trifluoromethyl Phenols.

AbstractFor Abstract see ChemInform Abstract in Full Text.