Intramolecular aromatic nucleophilic substitution of the benzimidazole-activated nitro group

A wide range of 2-(2-nitrophenyl)-1H-benzimidazoles undergo high-yielding intramolecular S(N)Ar of nitrite with N-pendant alkoxides under mild conditions (DMF, rt). When this operationally simple process is carried out at elevated temperatures in the presence of excess NaH, the initially formed S(N)Ar products are converted to the corresponding N-vinyl-substituted 2-(2-hydroxyphenyl)-1H-benzimidazoles via base-catalyzed isomerization. [reaction: see text]     

Synthesis of heterocycles on the basis of aliphatic nitro compounds (review)

The data on the synthesis of nitrogenous heterocycles on the basis of mononitroalkanes, polynitroalkanes, and alkenes have been generalized in this review. Only reactions in which the oxygen and nitrogen atoms of a nitro group appear in the composition of the heterocycle formed have been considered.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 435–452, April, 1986.     

An intramolecular nucleophilic substitution of oxetanes

The intramolecular attack of carbanions to oxetanes were examined and several three, five, and six membered carbocyclic compounds were synthesized.     

Synthesis of heterocyclic compounds on the basis of cyclohexane-1,3-diones (review)

The literature data for the period 1973–1985 on the synthesis, on the basis of cyclohexane-1,3-diones and their derivatives, of heterocyclic compounds that contain a 3-oxocyclohexene structural fragment or are formed as a result of a change in the cyclohexane ring are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 723–738, June, 1988.     

Quantum chemical study on the mechanisms of nucleophilic substitution of a nitro group in 2,4,6-trinitrotoluene and 1,3,5-trinitrobenzene

The semiempirical MNDO-PM3 method is employed for calculations of the enthalpies of formation of Meisenheimerortho- andipso--complexes of 1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT) with the methoxide ion in the gas phase and in water (using the pseudocontinual point-dipole solvation model). The calculated reaction enthalpies for the replacement of a TNB and TNT nitro group with a methoxy group reveal in principle the possibility for TNB to react with the methoxide ion in water by theS _NAr mechanism through an intermediateipso--complex. In the gas phase this reaction can not follow theS _NAr mechanism due to its strong endothermicity (20 kcal/mol). The analogous nucleophilic substitution of a TNT nitro group by a methoxy group may be suppressed by the faster formation of the stable trinitrobenzene anion.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1892–1897, November, 1993.     

Nitropyrazoles 21. Selective nucleophilic substitution of the nitro group in 1-amino-3,4-dinitropyrazole

Nucleophilic substitution of the nitro group in a model representative of N-aminopyrazoles, 1-amino-3,4-dinitropyrazole, has been studied for the first time. The compound was shown to undergo nucleophilic substitution with S-nucleophiles. The reaction was effected with regioselective substitution of the nitro group at position 3 and in good yields.     

Synthesis of heterocyclic geminal nitro azides

The oxidative azidation reactions of C-nitro-substituted saturated heterocyclic compounds, viz., the nitro derivatives of oxetane, azetidine, 1,3-dioxane, tetrahydro-1,3-oxazine, and hexahydropyrimidine, were investigated. A novel representatives of the geminal nitro azides were prepared and their physicochemical properties were studied. The process of the formation of the geminal dinitro compounds upon oxidative azidation was analyzed.     

Aromatic fluoro derivatives XLIX. Synthesis of carbocyclic compounds by intramolecular nucleophilic substitution reactions

Interaction of a compound of the type

with sodium hydride results in the formation of the Na salt of the carbanion

(where Ar_F represents a polyfluorinated group), which can enter into an intramolecular nucleophilic substitution reaction with the formation of the corresponding polyfluorinated carbocyclic compound. This reaction may serve as a general method for producing such compounds.     

Competitive nucleophilic substitution reactions of methylsulfonyl and nitro derivatives of polychloropyridines

2,6-Di(methylsulfonyl)-3,4,5-trichloropyridine (II) and 4-nitro-2,6-di(methyl-sulfonyl)-3, 5-dichloropyridine (IX) were synthesized, and their reactions with nucleophilic reagents were studied. It was found that the methylsulfonyl groups are replaced on reaction with alkali and sodium alkoxides; on reaction with amines, the chlorine atoms are replaced in the case of II and the nitro group is replaced in the case of IX. The nitro and methylsulfonyl groups are simultaneously replaced in the reaction of excess sodium methoxide with IX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 802–806, June, 1975.     

Preparation of SF5 aromatics by vicarious nucleophilic substitution reactions of nitro(pentafluorosulfanyl)benzenes with carbanions

Vicarious nucleophilic substitutions (VNS) of hydrogen in 1-nitro-4-(pentafluorosulfanyl)benzene with carbanions provide 2-substituted 1-nitro-4-(pentafluorosulfanyl)benzenes in good to high yields. VNS of 1-nitro-3-(pentafluorosulfanyl)benzene gives a mixture of 6- and 4-substituted 1-nitro-3-(pentafluorosulfanyl)benzenes in 85:15 to >98:2 ratio and good to high yields. In basic media, the VNS reactions lead to the formation of carbanions that can be alkylated by alkyl halides affording the corresponding alkylated products in moderate yields. Transformation of primary products to substituted (pentafluorosulfanyl)anilines and 3- or 4-substituted (pentafluorosulfanyl)benzenes is also described.     

Synthesis of heterocyclic compounds based on trichloroacetonitrile (review)

The available literature data on the utilization of trichloroacetonitrile in the synthesis of heterocyclic compounds are correlated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1443–1471, November, 1993.     

H-bond-assisted intramolecular nucleophilic displacement of the 1-NMe2 group in 1,8-bis(dimethylamino)naphthalenes as a route to multinuclear heterocyclic compounds and strained naphthalene derivatives

It has been shown that azomethines, hydrazones, and oximes derived from 2(7)-carbonyl derivatives of 1,8-bis(dimethylamino)naphthalene can undergo acid-catalyzed heterocyclization leading to a nucleophilic displacement of the 1-NMe(2) group. The process is believed to be directly connected with the proton sponge nature of the substrates, in which 1-NMe(2), being a poor leaving group, is preliminary activated via the formation of a chelated protonated form. A number of difficult to access derivatives of benzo[g]indazole, benzo[g]quinazoline, naphtho[2,1-d]isoxazole, and 8-dimethylamino-1-naphthol have been prepared in moderate to high yields.