Synthesis of Aryl 3,5-Dinitrophenyl Sulfones and Sulfoxides. Transformations of 3,5-Dinitrodiphenyl Sulfone in Reactions with O- and S-Nucleophiles

1-Arylthio-3,5-dinitrobenzenes are selectively oxidized to the corresponding sulfones and sulfoxides by the action of hydrogen peroxide. Reactions of 3,5-dinitrodiphenyl sulfone with O- and S-centered nucleophiles (RXH, X = O, S) in dipolar aprotic solvents in the presence of K₂CO₃ result in replacement of the nitro group by the RX fragment; the reaction with methanol occurs in aqueous medium in the presence of NaHCO₃. Substitution of the nitro group in 3,5-dinitrodiphenyl sulfone by phenylthio group, followed by oxidation of the sulfur atom to SO₂ and further replacement of the remaining nitro group yields 1,3,5-tris(phenylsulfonyl)benzene. The phenylsulfonyl group in the latter is replaced by phenylthio group by reaction with PhSH in the presence of K₂CO₃. Mononitrosulfones obtained by nucleophilic substitution in the title compound can be reduced to the corresponding anilines.     

Synthesis of peri-annelated heterocyclic systems based on 3-substituted 1-aryl-4,6-dinitro-1H-indazoles

A method for the synthesis of peri-annelated trinuclear heterocycles, including 14-electron heteroaromatic systems, namely, 1H-thiopyrano[4,3,2-cd]indazoles and 1,5-dihydropyrazolo[3,4,5-de]cinnolines, from 3-R-1-aryl-4,6-dinitro-1H-indazoles was developed. The method is based on the high mobility of the NO₂ group in position 4 and consists of either selective nucleophilic substitution of the 4-NO₂ group on treatment with the HSCH₂CO₂Me—K₂CO₃ system followed by intramolecular cyclization of the resulting sulfide (R = CHO) or the corresponding sulfone (R = CN) formed upon its oxidation or direct intramolecular substitution of the 4-NO₂ group (R = CH=NNHPh).     

Nitropyrazoles 17. Synthesis of 1-(3,5-dinitrophenyl)-4-methyl-3,5-dinitropyrazole and the study of its chemical transformations

A new one-step method for the synthesis of 4-methyl-3(5)-nitropyrazole by nitration of 4-methylpyrazole is developed. Arylation of 4-methyl-3(5)-nitropyrazole with 1,3,5-trinitrobenzene gives 1-(3,5-dinitrophenyl)-4-methyl-3-nitropyrazole, nitration of which leads to 1-(3,5-dinitrophenyl)-4-methyl-3,5-dinitropyrazole. The action of 1 equiv. of an O- or S-nucleophile (phenolate, p-chlorobenzenethiolate and ethoxide ions; anions of glycolanilide and thioglycolanilide) on 1-(3,5-dinitrophenyl)-4-methyl-3,5-dinitropyrazole led to the substitution of the 5-NO₂ group of the pyrazole ring; under the action of one more equivalent of a nucleophile the NO₂ group of the benzene ring was substituted. The substitution product of the anion of thioglycolanilide for the 5-NO₂ group undergoes the intramolecular cyclization — oxidative nucleophilic hydrogen substitution in the benzene ring under the action of K₂CO₃.     

Nucleophilic replacement of the nitro group in <Emphasis Type="Italic">E</Emphasis>-2,4,6-trinitrostilbenes by O- and S-nucleophiles. Synthesis of 2-aryl-4-X-6-nitrobenzo[<Emphasis Type="Italic">b</Emphasis>]thiophenes

The direction of nucleophilic substitution for the nitro group in E-2,4,6-trinitrostilbenes under the action of arene- and alkanethiols or phenols in the presence of inorganic bases was studied. Products of o-NO₂ group replacement in the presence of PhCH₂SH were used to obtain earlier unknown 2-aryl-4,6-dinitrobenzo[b]thiophenes and their 3-chloro derivatives. In these fused heterocycles, the 4-NO₂ group can be selectively displaced by a nucleophile.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 698–705, March, 2005.     

Characteristic features of nucleophilic substitution in the series of 4-RSO2-6-nitro-1-phenyl-1H-indazoles and benzo[d]isoxazoles

Oxidation of 3-substituted 4-R-6-nitro-1-phenyl-1H-indazoles and benzo[d]isoxazoles (R = Ph, CH₂CO₂Me) gave the corresponding sulfones treatment of which with PhSH—K₂CO₃ in N-methylpyrrolidone results in replacement of only the RSO₂ group in position 4 with the 6-NO₂ group remaining intact, contrary to the known sequence of nucleophilic substitution for meta-arranged nucleofuges.     

Intramolecular cyclization of O-(3,5-dinitrophenyl) and O-(3-amino-5-nitrophenyl) ketoximes, products of transformations of 1,3,5-trinitrobenzene. The synthesis of nitrobenzo[b]furans and 4-hydroxynitroindoles

O-(3,5-Dinitrophenyl) ketoximes obtained in the reactions of ketoximes with 1,3,5-trinitrobenzene undergo acid-catalyzed cyclization into 2-substituted or 2,3-disubstituted 4,6-dinitrobenzo[b]furans. In analogous cyclization, products of selective reduction of a nitro group in O-(3,5-dinitrophenyl) ketoximes unexpectedly yield, along with 6-amino-4-nitrobenzofurans, 4-hydroxy-6-nitroindoles. The 4-NO₂ group is displaced from 4,6-dinitrobenzo[b]furans in reactions with thiols in the presence of K₂CO₃. Conditions for nitration and sulfochlorination of 4,6-dinitrobenzo[b]furans in position 3 were found. Condensation of a 2-methyl derivative with dimethylformamide acetal was accomplished. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 984–991, May, 2007.     

Regioselective replacement of nitro groups in 2,4,6-trinitrotoluene under the action of alkanethiols. Synthesis of ortho-(alkylthio)-substituted nitrotoluenes and their oxidation to sulfoxides and sulfones

The reactions of 2,4,6-trinitrotoluene with alkanethiols in the presence of K₂CO₃ (the molar ratio of the reactants is 1 : 1 : 1) in dipolar aprotic solvents result in selective replacement of the ortho-nitro group to form 2-alkylthio-4,6-dinitrotoluenes, which can be oxidized to the corresponding sulfoxides or sulfones. The second ortho-nitro group can be replaced under the action of one more equivalent of alkanethiol on sulfides as exemplified in PhCH₂SH.     

Nitropyrazoles. 11. Isomeric 1-methyl-3(5)-nitropyrazole-4-carbonitriles in nucleophilic substitution reactions. Comparative reactivity of the nitro group in positions 3 and 5 of the pyrazole ring

With reactions of isomeric 1-methyl-3-nitro- and 1-methyl-5-nitropyrazole-4-carbonitriles with anionic S-, O-, and N-nucleophiles (RSH, PhOH, and 3,5-dimethyl-4-nitropyrazole in the presence of K₂CO₃ or MeONa), it was shown that for N-substituted 3(5)-nitropyrazoles, the nitro group in position 5 is much more reactive than in position 3.     

Silylation of γ-nitro ketones as a convenient approach to the synthesis of 2-[N,N-bis(silyloxy)amino]-2,3-dihydrofurans and conjugated enoximes

Silylation of -nitro ketones of the general formula R¹COCH(R²)CH(R³)CH(R⁴)NO₂ proceeded stereoselectively to give 2-[N,N-bis(trimethylsilyloxy)amino]-2,3-dihydrofurans, conjugated enoximes, silylation products of the carbonyl group or both functional groups, or N,N-bis(trimethylsilyloxy)enamine depending on the nature and positions of the substituents in the carbon skeleton. Dihydrofuran derivatives are formed for R¹ = Ar or cyclo-C₃H₅. Enoximes are generated as the silylation products of the starting ketones with enhanced -proton mobility (R³ = CO₂Me or 4-NO₂C₆H₄). The presence of an alkyl group at the carbonyl function (R¹ = Alk) is favorable for the formation of enoximes. Finally, the introduction of a substituent at the position with respect to the nitro group (R⁴ = Me, CO₂Me, or Ph) leads to the formation of silyl enolates. Under the action of NH₄F in MeOH, dihydrofurans can be transformed into substituted furans in moderate yields.     

Reactions of 1,3,5-trinitrobenzene with primary aliphatic alcohols

Analysis of reactions of 1,3,5-trinitrobenzene (TNB) with alcoholates of primary aliphatic alcohols (substitution of the nitro group or generation of σ^H-complexes at the unsubstituted position of TNB) leads to the conclusion that high basicity of alcoholates (MeONa, EtONa) of unsubstituted primary alcohols promotes formation of σ^H-complexes, thus preventing nucleophilic substitution of a nitro group. Introduction of electron-withdrawing substitutes (R = HC≡C, H₂C = CH, pyridyl) into the alcohol molecule (RCH₂OH) reduces the basicity of their alcoholates which makes substitution of nitro groups possible aff ording the corresponding 1-alkoxy-3,5-dinitrobenzenes in the presence of K₂CO₃ in N-methylpyrrolidone at 80 °C.     

Reaktionen von Tetraphosphortrichalkogeniden mit Alkyliodiden

Reactions of Tetraphosphorus Trichalcogenides with Alkyl Iodides Reactions of alkyl iodides RI (R = CHI₂, CH₂I or tert-Butyl) with P₄E₃ (E = S or Se) under the influence of light resulted in cleavage of the basal P₃ ring. β-P₄E₃(I)R was formed initially, then it rearranged to the more stable α-P₄E₃(I)R structure. ³¹P NMR data of these products were measured and discussed, along with ⁷⁷Se data for α- and β-P₄⁷⁷SeSe₂(I)CHI₂. On reaction of P₄S₃ with tert-butyl iodide in CS₂ or with sec-butyl iodide or iso-propyl iodide in dioxane, the new type of compounds P₅S₂R was observed. In this a sulfur bridge of P₄S₃ is replaced by a P? R group. ³¹P-NMR data for these compounds are reported.     

Regiospecificity of nucleophilic substitution in 4,6-dinitro-1-phenyl-1H-indazole

The reactions of 4,6-dinitro-1-phenyl-1H-indazole with anionic nucleophiles RS^– and N₃ ^– lead to the regiospecific replacement of the nitro group at position 4. The reaction with N₂H₄·H₂O + FeCl₃ also results in reduction of only the 4-NO₂ group. Based on this fact, a procedure was developed for the preparation of previously unknown 3-unsubstituted 4-X-6-nitro-1-phenyl-1H-indazoles (X is a residue of a nucleophile or NH₂). Comparison of the data on the selective nucleophilic substitution (4-NO₂ group) in 3-Z-1-aryl-4,6-dinitro-1H-indazoles shows that in the case of Z = H, the regiospecificity of substitution is determined by the electronic effect of the annelated pyrazole ring.     

INTERACTION OF 2,4,6-TRINITROTOLUENE AND ITS ANALOGUES WITH ALDEHYDES. SYNTHESIS OF BENZOANNELATED HETEROCYCLES FROM THE PRODUCTS OF CONDENSATION

ABSTRACT

2,4,6-Trinitrotoluene (TNT) and its sulfonyl analogue 2-isobutylsulphonyl-4,6-dinitrotoluene undergo smooth condensation with chloral and fluoral to give 2-R-4,6-dinitrophenyl-1-(trihalomethyl)ethanols which easily cyclize to give 4-R-6-nitro-2-trihalomethyl-2,3-dihydrobenzo[b]furans (R=NO₂, i-Bu; halogen = F or Cl) in the presence of K₂CO₃. 2-R′-sulphonyl-4,6-dinitrotoluenes, prepared from TNT, condense with aromatic aldehydes to form 1-(2-R′-sulphonyl-4,6-dinitro)-2-arylethenes in which the ortho-nitro group, upon interaction with NaN₃ was selectively substituted by the azido group. Thermolysis of the obtained azides gave 2-aryl-4-R′-sulphonyl-6-nitroindoles (R′ = Ph, i-Bu, PhCH₂). Such N-methylated indole (R′ = i-Bu) was regioselectively aminated.     

Investigation of reaction of dimedone and ethyl acetoacetate with 1,2-epoxy-3-chloropropane

Reactions of dimedone and ethyl acetoacetate with 1,2-epoxy-3-chloropropane in the presence of K₂CO₃ in DMSO medium were investigated. The reaction of 1,2-epoxy-3-chloropropane with ethyl acetoacetate afforded ethyl 5-hydroxy-2-methyl-5,6-dihydro-4H-pyran-3-carboxylate, with dimedone, 3-(1′,2′-epoxypropyloxy)-5,5-dimethyl-cyclohex-2-en-1-one.     

Transesterification Kinetics Investigation of R‐Substituted Phenyl Benzoates with 4‐Methoxyphenol in the Presence of K2CO3 in DMF

Transesterification of R‐substituted phenyl benzoates 1–5 with 4‐methoxyphenol 6 was kinetically investigated in the presence of K₂CO₃ in dimethylformamide (DMF) at various temperatures. The Hammett plots for the reactions of the 1–5 demonstrate good linear correlations with σ⁰ constants. Low magnitude of ρ_LG values indicate that the leaving group departure occurs after the rate‐determining step. The Brønsted coefficient values for the reactions (?0.2, ?0.16, ?0.13 at 15, 24, 36°C, respectively) demonstrate the weak effect of leaving group substituent on the reactivity of R‐substituted phenyl benzoates 1–5 for the reactions with 4‐methoxyphenol 6 in the presence of K₂CO₃ in DMF. The leaving group substituent effect on free energy (ΔG^≠), enthalpy (ΔH^≠), and entropy (ΔS^≠) of activation was examined. It was shown that the activation parameters obtained depend weakly on the leaving group substituent effect. The reaction is entropy controlled in case the leaving group substituent becomes electron withdrawing.     

Synthesis and properties of 5-chloro-4-nitropyrazoles

The nitration of 5-chloropyrazoles with a mixture of 100% nitric acid and 65% oleum or a mixture of 60% nitric acid and polyphosphoric acid gave substituted 5-chloro-4-nitropyrazoles in 45–91% yield. The nitration of 3-aryl-5-halopyrazoles was accompanied by introduction of a nitro group into the aromatic ring. 4-Chloropyrazoles failed to undergo nitration under these conditions. The reaction of 5-chloro-1,3-dimethyl-4-nitropyrazole with ethyl cyanoacetate in DMSO in the presence of K₂CO₃ led to the formation of ethyl 2-cyano-2-(1,3-dimethyl-4-nitro-1H-pyrazol-5-yl)acetate.     

Synthesis of Diaryl Ethers: A Long-Standing Problem Has Been Solved

A breakthrough in the synthesis of diaryl ethers has been achieved as shown in Equation (1). The coupling of phenols with aryl boronic acids in the presence of copper(II ) acetate and a base proceeds under very mild conditions (room temperature) as described simultaneously by Evans et al. and Chan et al. Examples: R¹=2-Cl, 2-I, 2-OMe, 4-tBu, 4-CH₂CH(NHCOOtBu)CO₂Me, 3,5-tBu₂; R²=2-Me, 3-OMe, 3-NO₂, 4-H, 4-F, 4-OMe.     

Synthesis of 3-Aryl[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3]benzothiazole-6,7-dicarbonitriles from 5-Aryl-4H-triazole-2-thiols and 5-Bromo-5-nitrophthalonitrile

New 3-aryl-substituted [1,2,4]triazolo][3,4-b][1,3]benzothiazole-6,7-dicarbonitriles have been synthesized by successive interaction of 5-aryl-4H-triazole-2-thiols with 4-bromo-5-nitrophthalonitrile in the presence of K₂CO₃ initially at the bromine atoms and then at the nitro group.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 270–272, February, 2005.     

Reactions of Cyclohexyl Isocyanide with η5‐Substituted Cyclo‐pentadienyl MoMo Triply Bonded Complexes. Crystal Structure of [Mo(CO)2(η5‐C5H4CO2CH3)]2(μ‐η2‐CNC6H11)

Reactions of one or two equiv. of cyclohexyl isocyanide in THF at room temperature with Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) gave the isocyanide coordinated Mo? Mo singly bonded complexes with functionally substituted cyclopentadienyl ligands, [Mo(CO)₂(η⁵‐C₅H₄R)]₂(μ‐η²‐CNC₆H₁₁) ( 1a , R=COCH₃; 1b , R=CO₂CH₃) and [Mo(CO)₂(η⁵‐C₅H₄R)(CNC₆H₁₁)]₂ ( 2a , R=COCH₃; 2b , R=CO₂CH₃), respectively. Complexes 1a , 1b and 2a , 2b could be more conveniently prepared by thermal decarbonylation of Mo? Mo singly bonded complexes [Mo(CO)₃(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in toluene at reflux, followed by treatment of the resulting Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in situ with cyclohexyl isocyanide. While 1a , 1b and 2a , 2b were characterized by elemental analysis and spectroscopy, 1b was further characterized by X‐ray crystallography.     

Coordination Germanium(IV) Compounds with Nitrosubstituted Benzoylhydrazones of Salicylaldehyde

New germanium(IV) complexes with N-[X-benzoyl]hydrazones of salicylaldehyde (X-H₂L, where X = 2-, 3-, and 4-NO₂; H₂L = C₆H₄–CO–NH–NCH–C₆H₄OH) with the compositions [Ge(2-NO₂–L)₂], [Ge(3-NO₂–L)₂], and [Ge(4-NO₂–L)₂] were synthesized. The data of IR, UV, and ¹H, ¹³C NMR spectroscopy showed that the complexes had an octahedral structure and ligand coordination through the nitrogen atom of the azomethine group and two oxygen atoms of the doubly deprotonated form of the ligand. The thermal stability of the complexes was studied. The specific features of the mass spectrometric behavior of the substances in the gas phase under electron impact were considered.