Synthesis of 3-R-2-aryl-4,6-dinitroindoles and specific features of their reactions with anionic nucleophiles

Reaction of different anionic S-nucleophiles with 3-R-2-aryl-4,6-dinitroindoles led to a regiospecific nucleophilic substitution of the nitro group in position 4 with 6-NO₂ group remaining intact. The representatives of some peri-annulated polycyclic systems were synthesized on the basis of the substitution products. Dedicated to Academician V. A. Tartakovsky in honor of his 75th anniversary. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1543–1547, August, 2007.     

Synthesis of 4,6-dinitro-3-R-benzo[d]isoxazoles and their transformations under the action of nucleophiles

A new procedure was developed for the preparation of 4,6-dinitro-3-R-benzo[d]isoxazoles (R are derivatives of the aldehyde group) based on 2,4,6-trinitrophenylacetaldehyde. The resulting compounds are characterized by the regiospecific substitution of the nitro group at position 4 under the action of anionic nucleophiles RS^–, RO^–, F^–, or N₃ ^–, which allowed the development of a new method for the preparation of previously unknown 4-Nu-6-nitro-3-R-benzo[d]isoxazoles (Nu is the residue of a nucleophile). At the same time, oxidative nucleophilic substitution under the action of anions of some -dicarbonyl compounds leads to the replacement of the hydrogen atom at position 7 with the corresponding C-nucleophiles.     

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.     

Synthesis of 3-cyano-4,6-dinitrobenzo[d]isoxazole and its reactions with anionic nucleophiles

The action of various anionic O-, N-, and S-nucleophiles on 3-cyano-4,6-dinitro-benzo[d]isoxazole mostly resulted in regiospecific nucleophilic substitution for the nitro group in position 4. With an excess of an nucleophilic reagent, the nitro group in position 6 was also replaced. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 523–528, March, 2006.     

Synthesis of 3-substituted 1-aryl-4,6-dinitro-1H-indazoles based on picrylacetaldehyde and their behavior in nucleophilic substitution reactions

A method for the synthesis of 1-aryl-3-formyl-4,6-dinitro-1H-indazoles by the reaction of picrylacetaldehyde with aryldiazonium salts followed by intramolecular cyclization of the resulting picrylglyoxal monoarylhydrazones was developed. Various 4,6-dinitro-1-phenyl-1H-indazoles substituted in position 3 were prepared via transformations involving the formyl group of 3-formyl-4,6-dinitro-1-phenyl-1H-indazole. 3-R-4,6-Dinitro-1-phenyl-1H-indazoles (R = CHO, CN, 1,3-dioxolan-2-yl) react regiospecifically with anionic O-, S-, and N-nucleophiles, in particular, with replacement of only the 4-NO₂ group. Thus previously unknown 3-R-4-Nu-6-nitro-1-phenyl-1H-indazoles were synthesized (Nu is a nucleophile residue).     

Synthesis of brominated 2-(tert-butyl-NNO-azoxy)anilmes

2-(tert-Butyl-NNO-azoxy)aniline was prepared by selective reduction of 2-(tert-butyl-NNO-azoxy)nitrobenzene. Its bromination yielded the correspondingpara-bromo- andortho, para-dibromoanilines (3a,b).meta-Bromoanilines (6a,b) were synthesized by selective replacement of theortho-bromine atoms in ortho,para-bromo(tert-butylazoxy)benzenes (5a,b) by ammonia in toluene under pressure.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1620–1623, September, 1994.This work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-18461).     

Nucleophilic Functionalization of 2-R-3-Nitropyridines as a Versatile Approach to Novel Fluorescent Molecules

A number of new 2-methyl- and 2-arylvinyl-3-nitropyridines were synthesized and their reactions with thiols were studied. It was found that 3-NO₂ tends to be selectively substituted under the action of sulfur nucleophiles in the presence of another nucleofuge in position 5. Correlations between the substitution pattern and regioselectivity as well as photophysical properties were established. Some synthesized compounds possessed a large Stokes shift.     

Nucleophilic Functionalization of 2-Alkylidene-4-Oxothiazolidines at C(5)-Position Induced by Formation of Novel Pyridinium Salt

Abstract

The synthesis of unsubstituted pyridinium salt containing the 4-oxothiazolidine moiety bondedviaC(5) to the N position of the pyridine nucleus is reported. The nucleophilic displacement of pyridine from pyridinium salt by the selected nucleophiles leads to the formation of new 5-substituted 4-oxothiazolidines in good yields.     

Amination of 4-Azafluorene under Chichibabin Reaction Conditions. Some Chemical Transformations of 1-Amino-4-azafluorene

4-Azafluorene is aminated by sodium amide in dimethylaniline at C₍₁₎. The oxidation of 1-amino-4-azafluorene was studied along with the condensation of this compound with acetic anhydride and its diazotization.     

Synthesis of 2-Amino- and 2-Hydrazino-substituted 5-Nitro-4,6-diphenylpyrimidines

Nitrogen-containing derivatives of 5-nitro-4,6-diphenylpyrimidine have been synthesized by the reaction of 2-chloro-5-nitro-4,6-diphenylpyrimidine with amines or of 2-hydrazino-5-nitro-4,6-diphenylpyrimidine with carbonyl or -dicarbonyl compounds. Their structures were confirmed by data of IR spectroscopy and mass spectrometry.     

Nucleophilic aromatic substitution of hydrogen through lithiated phosphine borane complexes and N-phosphorylphosphazenes

Organophosphorus compounds containing nitroaryl and cyanoaryl groups have been prepared in good yield through nucleophilic aromatic substitution of hydrogen using α-lithiated phosphazenes and phosphine borane complexes as nucleophiles. In all cases, nearly exclusive replacement of the hydrogen in the para position with respect to the activating group has been observed.     

2,5-二甲氧基-4-氯硝基苯与硫化钠的反应

硫化钠和二硫化钠分别在95%乙醇中与2,5-二甲氧基-4-氯硝基苯反应, 原本期望得到2,5-二甲氧基-4-氯苯胺, 然而对产物结构的1H NMR, 13C NMR, MS以及元素分析结果表明, 2,5-二甲氧基-4-氯硝基苯中的硝基没有被硫化钠和二硫化钠还原成氨基, 而是其中的氯原子被硫离子(或二硫离子)取代, 分别生成了4,4’-硫代-2,2’,5,5’-四甲氧基-双硝基苯和4,4’-双硫代-2,2’,5,5’-四甲氧基-双硝基苯. 根据这个实验事实, 讨论了上述亲核取代反应的机理.     

相转移催化法实现聚苯乙烯的功能化转变

以对羟基苯甲醛的钠盐为亲核取代试剂,采用相转移催化进行了大分子氯甲基聚苯乙烯的亲核取代反应,将其转变为侧链带有功能性基团醛基的聚苯乙烯;考察了反应条件(如有机溶剂的极性、催化剂种类及用量、有机相与水相之比等)对大分子相转移催化反应的影响,并根据相转移催化反应机理与相关的动力学规律进行了分析.结果表明,通过相转移催化亲核取代反应,可将氯甲基聚苯乙烯大分子链上的氯原子转化,制得侧链带有醛基的聚苯乙烯;溶剂的极性越强,负离子的反应活性也越高;催化剂季铵正离子的亲脂性越强,相转移催化反应的速率越快.当催化剂浓度较低时,四丁基溴化铵比十六烷基溴化铵的催化效果好;当催化剂浓度较高时,十六烷基溴化铵比四丁基溴化铵的催化效果好.另外,有机相与水相之比对相转移催化反应有较大的影响.     

硝基芳环和硝基杂芳环中氢的替代亲核取代

氢的替代亲核取代反应(VNS)是与硝基芳环的亲电反应、亲核反应不同的一种新反应. 将VNS与硝基芳环的亲电反应、亲核反应做比较, 阐述了VNS的定义; 通过对竞比实验、速控步骤和动力学同位素效应的分析, 解释了VNS的反应机理; 分别从硝基芳环的结构、亲核试剂的类型和反应条件三方面讨论了影响VNS定位效应的因素; 介绍了VNS反应的应用, 尤其是VNS胺化反应在军事化学中的实际应用.     

Catalytic Functionalization of Indoles in a New Dimension

140 Years ago Adolf von Baeyer proposed the structure of a heteroaromatic compound which revolutionized organic and medical chemistry: indole. After more than a century, indole itself and the complexity of naturally occurring indole derivatives continue to inspire and influence developments in synthetic chemistry. In particular, the ubiquitous presence of indole rings in pharmaceuticals, agrochemicals, and functional materials are testament to the ever increasing interest in the design of mild and efficient synthetic routes to functionalized indole derivatives. This Review emphasizes the achievements in the selective catalytic functionalization of indoles (C? C bond‐forming processes) over the last four years.     

Vicarious Nucleophilic Substitution of Hydrogen in Nitro-substituted Pyrroles, Azoles, and Benzannelated Systems Based on Them. (Review)

Published data on the participation of nitro-substituted pyrroles, azoles, and their benzannelated derivatives in vicarious nucleophilic substitution are reviewed.     

Homologous SNV Reaction: Synthesis of l‐Methyl‐4‐[4′‐phenylsulfonyl‐1′,3′‐butadienyl]pyridinium Iodide and Its Reactivity with Thiol Groups Giving Rise to the Chromophoric Thioether

Thioether 4‐[(1′E,3′E)‐4′‐phenylsulfanyl‐1,3′‐butadienyl]pyridine 8 and sulfone 4‐(4′‐phenylsulfonyl‐1′,3′‐butadienyl)pyridine 14 were prepared by reaction of the carbanions derived from allylic thioether or allylic sulfone with isonicotinaldehyde. The reaction with the sulfonyl carbanion occurred at the α position and on heating the alcolate gave the dienic sulfone 14 . The corresponding pyridinium iodide 10 and 15 were prepared by reaction with methyl iodide, respectively, on pyridine derivates 8 and 14 . The dienic pyridinium thioether 10 showed a long wavelength absorption band centered at 420 nm. The reaction of dienic pyridinium sulfone 15 with thiophenol gave the dienic pyridinium thioether 10 by a nucleophilic vinylic substitution. The reaction of sulfone 15 with glutathione was of second order and the rate constant was 8.5 M^?1s^?1 at 30°C and pH 7, about 500 times smaller than the rate constant observed with (E)‐1‐methyl‐4‐(2‐methylsulfonyl‐1‐ethenyl)pyridinium iodide 1 . The dienic pyridinium thioether 10 was a negative solvatochrome.     

Reaction of 1-Acetyl-5-hydroxy-2-phenylpyrazolidines with Amino Acid Esters

Reaction of 1-acetyl-2-phenyl-5-hydroxypyrazolidines with amino acid esters occurs to give the corresponding N-pyrazolidinyl amino acids under mild conditions.     

Intramolecular nucleophilic substitution at an sp carbon: synthesis of substituted thiazoles and imidazole-2-thiones

The nucleophilic substitution reactions of vinylic bromides with intramolecular thioamide or thiourea moieties proceed to give a series of substituted thiazoles and imidazole-2-thiones.