Reaction of 3,4,6-trioxoalkanoic acid esters with 2,4-dinitrophenylhydrazine

Methyl 3,4,6-trioxoalkanoates (3,4-dihydroxy-6-oxo-2,4-alkadienoates) reacted with 2,4-dinitrophenylhydrazine to give methyl 3,6-bis[(2,4-dinitrophenyl)hydrazinylidene]-4-oxoalkanoates or methyl {5-alkyl-2-hydroxy-1-(2,4-dinitroanilino)-3-oxo-2,3-dihydro-1H-pyrrol-2-yl }acetates. Alkyl 3,6-bis[(2,4-dinitrophenyl) hydrazinylidene]-4-oxoalkanoates were also synthesized by reaction of disodium 1-alkoxy-1,6-dioxoalka-2,4-diene-3,4-diolates with 2,4-dinitrophenylhydrazine.     

Reaction of 3,4-dioxohexane-1,6-dioic acid esters with 2,4-dinitrophenylhydrazine

Reaction was studied of 3,4-dihydroxyhexa-2,4-diene-1,6-dioic acid esters with 2,4-dinitrophenylhydrazine that led to the formation of esters of (3E)-3-[2-(2,4-dinitrophenyl)-hydrazinylidene]-4-oxohexane-1,6-dioic and (3E,4E)-3,4-bis[2-(2,4-dinitrophenyl)hydrazinylidene]-hexane-1,6-dioic acids. The structural features of compounds synthesized were established from the data of IR and NMR spectra and X-ray diffraction (XRD) analysis.     

Synthesis of N-aminopyrazoles by Fe(II)-catalyzed rearrangement of 4-hydrazonomethyl-substituted isoxazoles

A novel effective method is reported for the preparation of 1-amino-1H-pyrazole-4-carboxylic acid derivatives by Fe(II)-catalyzed rearrangement of isoxazoles having (2,4-dinitrophenylhydrazono)methyl substituent at C4. The reaction proceeds smoothly for both E and Z isomers of 4-(hydrazonomethyl)isoxazoles, and this means it is not necessary to separate mixtures of E/Z-isomers of the hydrazones prepared by reaction of 5-methoxy/pirrolidino-4-carbonylisoxazoles and 2,4-dinitrophenylhydrazine. The rearrangement proceeds via the formation of an aziridine intermediate which can be isolated in certain cases. The 2-nitro group in the synthesized 1-[(2,4-dinitrophenyl)amino]-1H-pyrazole-4-carboxylic esters can be selectively reduced in two steps via acylation of the amino group followed by hydrogenation-deacylation using H₂-Pd/C.     

Reaction of bis(2,4-dinitrophenyl) phosphate with hydrazine and hydrogen peroxide. Comparison of O- and N- phosphorylation

Nonionic hydrazine reacts with anionic bis(2,4-dinitrophenyl) phosphate (BDNPP), giving 2,4-dinitrophenyl hydrazine and dianionic 2,4-dinitrophenyl phosphate by an S(N)2(Ar) reaction, and at the phosphoryl center, giving 2,4-dinitrophenoxide ion and a transient phosphorylated hydrazine that rearranges intramolecularly to N-(2,4-dinitrophenyl)-N-phosphonohydrazine. Approximately 58% of the reaction at pD = 10 occurs by N-phosphorylation, as shown by (31)P NMR spectroscopy. Reaction of HO(2)(-) is wholly at phosphorus, and the intermediate peroxophosphate reacts intramolecularly, displacing a second 2,4-dinitrophenoxide ion, or with H(2)O(2), giving 2,4-dinitrophenyl phosphate and O(2). Rate constants of O- and N-phosphorylation in reactions at phosphorus of NH(2)NH(2), HO(2)(-), and NH(2)OH and its methyl derivatives follow Bronsted relationships with similar slopes, but plots differ for oxygen and nitrogen nucleophiles. The reaction with NH(2)NH(2) has been probed by using both NMR spectroscopy and electrospray ionization mass and tandem mass spectrometry, with the novel interception of key reaction intermediates in the course of reaction.     

Synthesis, structure, and isomerism of N-2,4-dinitrophenylbenzotriazoles

Both isomers of N-(2′,4′-dinitrophenyl)benzotriazole, the 1(3)- and the 2-substituted, have been characterized and their reciprocal isomerism was studied. Cross-experiments in the presence of 5(6)-nitro-1H-benzotriazole proved that the isomerization of 2-(2′,4′-dinitrophenyl)-2H-benzotriazole into the 1-isomer occurs by an intermolecular mechanism. The reported reaction of 5(6)-nitro-1H-benzotriazole with 1-chloro-2,4-dinitrobenzene has been reexamined discovering that there is an error in the proportions of N-substituted isomers. A possible explanation for the observed isomerizations was proposed. Identification of all compounds by multinuclear magnetic resonance, including solid-state studies, has been achieved.     

Selection of phage antibodies with GPX activity by combination of phage displayed antibody library with chemical modification and their characterization using a surface plasmon resonance biosensor

Glutathione peroxidase (GPX) is an important antioxidant enzyme, which plays an important role in scavenging reactive oxygen species. To obtain humanized GPX catalytic antibodies, the phage displayed human antibody library on the surface of the filamentous bacteriophage was used to select novel antibodies by repetitive screening. Phage antibodies B8, H6 and C1 with the GSH-binding site were obtained from the library by enzyme-linked immunosorbent assay (ELISA) analysis with four rounds of selection against three haptens, S-2,4-dinitrophenyl t-butyl ester [GSH-S-DNP-Bu (B)], S-2,4-dinitrophenyl t-hexyl ester [GSH-S-DNP-He (H)] and S-2,4-dinitrophenyl cycle-hexyl ester [GSH-S-DNP-cHe (C)], and characterized using surface plasmon resonance (SPR) biosensor. The gold layer was modified by dithiodiglycolic acid (DDA) and three haptens were easily attached to DDA by self-assembling to form a biosensor membrane. The membrane bounds specifically corresponding antibodies. The kinetic process of the reaction between phage antibodies and their haptens was studied by SPR biosensor. In order to improve selectivity, chemical modification was used to incorporate directly catalytic group selenocysteine (Sec) into selected phage clone B8, H6 and C1 to form Se-B8, Se-H6 and Se-C1, respectively. The GPX activities of Se-B8, Se-H6 and Se-C1 were found to be 3000, 2000 and 700 units/μmol, respectively. Compared with conventional ELISA analysis, the proposed method based on SPR biosensor is much more rapid and simpler.     

Nitropyrazoles 15. Synthesis and some transformations of 1-(2,4-dinitrophenyl)-4-methyl-3,5-dinitropyrazole

The method for preparation of 1-(2,4-dinitrophenyl)-4-methyl-3,5-dinitropyrazole has been developed. Due to the larger CH-acidity of 4-Me-group compared to 1,4-dimethyl-3,5-dinitropyrazole, 1-(2,4-dinitrophenyl)-4-methyl-3,5-dinitropyrazole is capable of reacting with substituted benzaldehydes to afford 4-[(E)-2-arylvinyl]-1-(2,4-dinitrophenyl)-3,5-dinitropyrazoles. Under the action of nucleophiles, dinitrophenyl group is detached from the former compounds leading to previously unknown N-unsubstituted 4-[(E)-2-arylvinyl]-3,5-dinitropyrazoles.     

Ion-selective electrodes in titrations involving azo-coupling reactions: Part 4. Determination of Secondary Amines

The determination of secondary amines (1–10 mg) is based on their reaction with arenediazonium ions to form triazenes. The sample is mixed with 4-bromo-1-naphthalenediazonium chloride and, when the coupling reaction is complete, the excess of diazonium salt is back-titrated with sodium tetraphenylborate. The end-point is easily evaluated from the sigmoidal potentiometric titration curves recorded with a PVC membrane indicating electrode plasticized with 2,4-dinitrophenyl n-octyl ether. Diethylamine, diethanolamine, piperidine, N-ethylaniline and 1-(N-methyl)amino-9,10-anthraquinone were used as test compounds.     

Reactions of bis(2,4-dinitrophenyl) phosphate with hydroxylamine

For dephosphorylation of bis(2,4-dinitrophenyl) phosphate (BDNPP) by hydroxylamine in water, pH region 4-12, the observed first-order rate constant, k(obs), initially increases as a function of pH, but is pH-independent between pH 7.2 and pH 10. The initial BDNPP cleavage by nonionic NH(2)OH (<0.2 M) involves attack by the OH group and follows first-order kinetics, but the overall initial reaction of BDNPP liberates ca. 1.7 mol of 2,4-dinitrophenoxide ion (DNP). This initial reaction generates a short-lived O-phosphorylated hydroxylamine, 2, followed by three possible reactions: (1) reaction of 2 with hydroxylamine, generating 2,4-dinitrophenyl phosphate (DNPP, 3), which subsequently forms DNP; (2) intramolecular displacement of the second DNP group and rapid decomposition of the cyclic intermediate to form phosphonohydroxylamine and eventually inorganic phosphate; (3) a novel rearrangement with intramolecular aromatic nucleophilic substitution involving a cyclic intermediate and migration of the 2,4-dinitrophenyl group from O to N. Values of k(obs) increase modestly with pH > 10, the reaction is biphasic, and the yield of DNP increases. An increase in [NH(2)OH] also increases the yield of DNP, due largely to accelerated hydrolysis of DNPP.     

New approach for the synthesis of 1-aryl- and 1-heteroaryl-5-nitrouracil derivatives

1-(2,4-Dinitrophenyl)-5-nitrouracil and its 3-methyl derivatives were synthesized and used as substrates in reaction with aromatic amines and amino pyridines. In the reaction of aniline with 1-(2,4-dinitrophenyl)-5-nitrouracil, only the acyclic adduct was isolated. When 1-(2,4-dinitrophenyl)-3-methyl-5-nitrouracil was treated with aniline and other aromatic amines or amino pyridines, the desired 1-aryl-5-nitrouracil derivatives were obtained in satisfactory yield. The influence of the free H-3 proton present in the uracil ring on the course of the reaction is discussed.     

An Abnormal Reaction of N-(2,4-dinitrophenyl)-L-proline with Thionyl Chloride

N-(2,4-Dinitrophenyl)-4-amino-n-butyl aldehyde 3 was obtained with high yield of 80% when N-(2,4-dinitrophenyl)-L-proline 1 reacted with SOCl2 at room temperature,However,the anticipated product N-(2,4-dinitrophenyl)-Tetrahydropyrrolyl-2-(4-methylthiophenyl)ketone 2 did not be produced.The mechanism was discussed in this article.     

Hydrogen bonding and sodium coordination in the crystal structure of tetrasodium (3-((2,4-dinitrophenyl)amino)-1-hydroxypropane-1,1-diyl)-bis-phosphonate pentahydrate – a N-substituted Pamidronate

The reaction of 1-fluoro-2,4-dinitrobenzene with (3-amino-1-hydroxypropane-1,1-diyl)bis(phosphonic acid) (pamidronic acid) 1a in combination with NAOH leads to disodium (3-((2,4-dinitrophenyl)amino)-1-hydroxy-propane-1,1-diyl)bis(phosphonate) heptahydrate 2 and further to tetrasodium (3-((2,4-dinitrophenyl)amino)-1-hydroxy-propane-1,1-diyl)bis(phosphonate) pentahydrate 3. The crystal structure of 3 is composed of the organic anion, which is coordinated to the sodium counter cations and furthermore is involved in hydrogen bonds. The 2,4-dinitrophenyl moiety gives rise to π–π connected hydrophobic layers. The hydrophilic moiety of the anions, sodium cations and water molecules form a hydrophilic layer. The individual conformation of this N-substituted pamidronate anion is a compromise between its geometric limitations and the intermolecular interactions with sodium and the water molecules.     

Synthesis of pyrrolo[3,2,1-hi]indazoles from indole-7-ketoximes

Treatment of the 2,4-dinitrophenyl ethers of some indole-7-ketoximes with base results in a cyclisation reaction to yield pyrrolo[3,2,1-hi]indazoles.     

Synthesis of indolo[2,3-c]quinolines from 3-arylindole-2-ketoximes

Treatment of the 2,4-dinitrophenyl ethers of some 3-arylindole-2-ketoximes with base results in a cyclisation reaction to yield indolo[2,3-c]quinolines.     

Kinetics and mechanism of the pyridinolysis of S-2,4-dinitrophenyl 4-substituted thiobenzoates

[reaction: see text] The reactions of S-2,4-dinitrophenyl 4-methyl (1), S-2,4-dinitrophenyl 4-H (2), S-2,4-dinitrophenyl 4-chloro (3), and S-2,4-dinitrophenyl 4-nitro (4) thiobenzoates with a structurally homogeneous series of pyridines are subjected to a kinetic investigation in 44 wt % ethanol-water, at 25.0 degrees C and an ionic strength of 0.2 M (KCl). The reactions are studied spectrophotometrically (420 nm) by monitoring the appearance of 2,4-dinitrobenzenethiolate anion. Pseudo-first-order rate coefficients (k(obsd)) are obtained for all the reactions, employing excess of amine. The plots of k(obsd) vs [free pyridine] at constant pH are linear with the slopes (k(N)) independent of pH. The Br?nsted-type plots (log k(N) vs pK(a) of the conjugate acid of the pyridines) are curved for all the reactions. The Br?nsted curves are in accordance with stepwise mechanisms, through a zwitterionic tetrahedral intermediate (T(+/-)), and a change in the rate-limiting step. An equation based on this hypothesis accounts well for the experimental points. The Br?nsted lines were calculated with the following parameters: Reactions of thiolbenzoate 1: beta(1) 0.33 (slope at high pK(a)), beta(2) 0.95 (slope at low pK(a)), and pK(a)(0) = 8.5 (pK(a) at the curvature center); thiolbenzoate 2: beta(1) 0.30, beta(2) 0.88, and pK(a)(0) = 8.9; thiolbenzoate 3: beta(1) 0.33, beta(2) 0.89, and pK(a)(0) = 9.5; thiolbenzoate 4: beta(1) 0.21, beta(2) 0.97, and pK(a)(0) = 9.9. The increase of the pK(a)(0) value with the increase of the electron-withdrawing effect of the acyl substituent is explained by the argument that the rate of pyridine expulsion from T(+/-) (k(-)(1)) is favored over that of 2,4-dinitrobenzenethiolate leaving (k(2)), i.e., k(-)(1)/k(2) increases, as the acyl group becomes more electron withdrawing. The pK(a)(0) values for the title reactions are smaller than those for the reactions of the corresponding 4-nitrophenyl 4-substituted thiolbenzoates with the same pyridine series. This is explained by the larger k(2) value for 2,4-dinitrobenzenethiolate leaving from T(+/-) compared with 4-nitrobenzenethiolate, which results in lower k(-)(1)/k(2) ratios for the dinitro derivatives. The pK(a)(0) value obtained for the pyridinolysis of thiolbenzoate 2 (pK(a)(0) = 8.9) is smaller than that found for the same aminolysis of 2,4-dinitrophenyl benzoate (pK(a)(0) = 9.5). This is attributed to the greater nucleofugality from T(+/-) of 2,4-dinitrobenzenethiolate (pK(a) of conjugate acid 3.4) relative to 2,4-dinitrophenoxide (pK(a) of conjugate acid 4.1). The title reactions are also compared with the aminolysis of similar esters to assess the effect of the amine nature and leaving and acyl groups on the kinetics and mechanism.     

Unusual dealkylations and rearrangements in aromatic nucleophilic substitution

The reaction of 2,4-dinitrohalobenzenes with di-isopropylamine produces mainly N-(2,4-dinitrophenyl)-isopropylamine and N-(2,4-dinitrophenyl)-n-propylamine instead of the expected straightforward substitution product. Dealkylations are also observed in the reactions with isopropylcyclohexylamine and dicyclohexylamine. A carbanionic mechanism is proposed.     

Iron(0) nanoparticles mediated direct conversion of aryl/heteroaryl amines to chalcogenides via in situ diazotization

A simple procedure for the synthesis of organo-chalcogenides has been developed by the reaction of aryl/heteroaryl amines with di-aryl/heteroaryl dichalcogenides in the presence of ^tBuONO and Fe(0) nanoparticles. The reaction proceeds via in situ diazotization followed by chalcogenation. A series of functionalized diaryl/aryl heteroaryl/diheteroaryl/aryl-alkyl selenides, sulfides and tellurides have been obtained by this procedure. Significantly, using this procedure 2,4-dinitroaniline is converted to (2,4-dinitrophenyl)(phenyl)selane which is known as thioredoxin reductase (TR) and glutathione reductase (GR) inhibitor. The reaction goes by a radical pathway and a plausible mechanism has been suggested.     

Novel routes to N-amino-1H-pyrrolo[2,3-b]pyridines from α-hydroxyarylalkyl ketones and hydrazines

Treatment of 3-hydroxy-3-(3-pyridyl)butan-2-one hydrazone with polyphosphoric acid gave 1-amino-2,3-dimethyl-1H-pyrrolo[2,3-b]pyridine. An analogous reaction with 2,4-dinitrophenylhydrazone of the same ketone yielded 1-(2,4-dinitrophenyl)-3-methyl-4-(3-pyridyl)pyrazole. Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1552–1556, August, 2007.     

Simultaneous enantiomeric determination of MDMA and its phase I and phase II metabolites in urine by liquid chromatography–tandem mass spectrometry with chiral derivatization

A liquid chromatography–electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) procedure was developed for the simultaneous determination of enantiomers of the prevalent designer drug 3,4-methylenedioxymethamphetamine (MDMA) and its phase I and phase II metabolites in urine with chiral derivatization. The analytes in urine were directly derivatized with chiral Marfey’s reagent, N ^α- (5-fluoro-2,4-dinitrophenyl)-d-leucinamide, without extraction. The diastereomers of the N ^α-(2,4-dinitrophenyl)-d-leucinamide derivatives generated were determined by LC-MS/MS. Satisfactory chromatographic separation was achieved for the enantiomers of MDMA and its metabolites 3,4-methylenedioxyamphetamine, 4-hydroxy-3-methoxymethamphetamine (HMMA), HMMA glucuronide, and HMMA sulfate on a semimicro octadecylsilane column using linear gradient elution. With use of multiple reaction monitoring mode, the limits of detection of these analytes ranged from 0.01 to 0.03?μg/mL. Linear calibration curves were obtained for all enantiomers from 0.1 to 20?μg/mL in urine. The method showed sufficient reproducibility and quantitative ability. This is the first report of a simple LC-MS/MS-based analytical procedure with direct chiral derivatization in aqueous media that allows simultaneous enantiomeric determination of drugs and their metabolites, including glucuronide and sulfate derivatives.     

An investigation of the structure of the nitration products of 1-phenyl-5-styryltetrazole using the mass-spectrometric method

Depending on the reaction conditions, the nitration of 1-phenyl-5-styryltetrazole (I) with nitric acid and nitrating mixture give 1-(4-nitrophenyl)-5-styryltetrazole, 1-(4-nitrophenyl)-5-(4-nitrostyryltetrazole), and 1-(2,4-dinitrophenyl)-5-(4-nitrostyryl) tetrazole. The structures of the compounds obtained have been established by an analysis of their mass spectra and of the mass spectra of model compounds. The positions and sequences of entry of the nitro groups have been determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 558–563, April, 1980.