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Mieczyslaw Makosza - One of the best experts on this subject based on the ideXlab platform.
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deoxygenative vs Vicarious Nucleophilic Substitution of hydrogen in reactions of 1 2 4 triazine 4 oxides with α halocarbanions
European Journal of Organic Chemistry, 2002Co-Authors: D N Kozhevnikov, Mieczyslaw Makosza, Andrzej Rykowski, Vladimir L Rusinov, O N Chupakhin, Ewa WolinskaAbstract:The 3,6-diaryl-1,2,4-triazine 4-oxides 1a−e undergo a Nucleophilic Substitution of hydrogen with the α-halomethyl aryl sulfones 2, 3 and 7 by two alternative pathways: Vicarious Nucleophilic Substitution (VNS) and/or an intramolecular deoxygenative process. The former pathway is found to dominate in the reaction of 1 with bromomethyl tolyl sulfone (7) yielding the 5-tosylmethyl-1,2,4-triazine 4-oxides 6, while the reaction with the chloromethyl aryl sulfones 2 and 3 leads to the 5-arylsulfonylchloromethyl-1,2,4-triazines 4 and 5, respectively, as the products of deoxygenative Substitution. The reaction of 6-phenyl-1,2,4-triazine 4-oxide (1f) with the chloromethyl aryl sulfones 2 and 3 proceeds differently. At low temperature (−75 C) the products of the VNS reaction at position 5 (6f and 12f) are formed. At room temperature the 7-chloro-1-hydroxy-3-phenyl-7-(arylsulfonyl)-1,4,5-triazahepta-1,3,6-trienes 10f and 11f are obtained by addition of the carbanions 2 and 3 in the 3-position, followed by the ring opening of the resulting σ adduct. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)
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elucidation of the Vicarious Nucleophilic Substitution of hydrogen mechanism via studies of competition between Substitution of hydrogen deuterium and fluorine
Journal of Organic Chemistry, 2002Co-Authors: Mieczyslaw Makosza, Andrzej Kwast, Tadeusz Lemek, Francois TerrierAbstract:Relations of rates of the Vicarious Nucleophilic Substitution of hydrogen (VNS) and SNAr Substitution of fluorine in 2-fluoronitrobenzenes with chloroalkyl aryl sulfone carbanions were determined from competitive experiments carried out at various concentrations of base. The observed dependence of the VNS/SNAr rate ratio on the base concentration confirmed the two-step mechanism of the VNS, which consists of reversible formation of σH adducts of the α-chlorocarbanion to nitroarene, followed by base-induced β-elimination of HCl. It was also evidenced that both of these processes can be the rate-limiting steps: the β-elimination at low base concentration and the Nucleophilic addition at high base concentration. Consistent with that conclusion is the finding that the kinetic isotope effect in the VNS reaction decreases from 4.2 (a value typical of a primary KIE) to 0.8 (a value typical of a secondary KIE) with increasing base concentration. Also reported is our discovery that the SNAr Substitution of the 2-...
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hydroxylation and amination of azulenes by Vicarious Nucleophilic Substitution of hydrogen
European Journal of Organic Chemistry, 2000Co-Authors: Mieczyslaw Makosza, Renata PodrazaAbstract:Hydroxylation of azulenes with tert-butylhydroperoxide proceeds efficiently at the 6-position when the former contain electron-withdrawing substituents in the five-membered ring. Similarly, VNS amination of azulenes proceeds with 4-amino-1,2,4-triazole; its anion, being an active nucleophile, also reacts with unsubstituted azulene. A variety of transformations of 6-hydroxyazulenes, such as Substitution of the corresponding sulfonates with nitrogen, oxygen, sulfur, carbon nucleophiles and halogens, and the Claisen rearrangement of allylic ethers, is reported.
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oxidative Nucleophilic Substitution of hydrogen in nitroarenes with phenylacetonitrile derivatives
Tetrahedron, 1998Co-Authors: Mieczyslaw Makosza, Krzysztof StalinskiAbstract:Abstract Tertiary carbanions generated from α-substituted phenylacetonitriles in liquid ammonia add to nitro-benzenes in the para position to form the corresponding σH-adducts which are transformed, depending on the starting nitriles and the reaction conditions, to products of oxidative Nucleophilic Substitution of hydrogen, ONSH or Vicarious Nucleophilic Substitution, VNS.
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nitroarylamines via the Vicarious Nucleophilic Substitution of hydrogen amination alkylamination and arylamination of nitroarenes with sulfenamides
Journal of Organic Chemistry, 1998Co-Authors: Mieczyslaw Makosza, Maciej BialeckiAbstract:A new reaction of sulfenamides with electrophilic arenes under basic conditions is described. The σ adducts formed from nitroarenes and the anions of sulfenamides undergo elimination of thiol to produce the corresponding o- and/or p-nitroanilines. This reaction is analogous to the known alkylation and hydroxylation of nitroarenes via the Vicarious Nucleophilic Substitution of hydrogen (VNS). The reaction gives access to a wide range of substituted nitroanilines, nitronaphthylamines, and aminoheterocycles. By means of the reaction with N-alkyl- and N-arylsulfenamides, it is possible to obtain N-alkylnitroanilines and nitrodiarylamines. By varying the structure of sulfenamide and the reaction conditions, particularly the nature and concentration of the base, it is possible to control the orientation of amination.
Mieczyslaw Mąkosza - One of the best experts on this subject based on the ideXlab platform.
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simple synthesis of dimethyl nitrobenzhydrylphosphonates and heteroarylnitroarylacetonitriles via Vicarious Nucleophilic Substitution vns reaction
Synthesis, 2020Co-Authors: Mieczyslaw Mąkosza, Malgorzata Bechcicka, Krzysztof WojciechowskiAbstract:Acetals of dimethyl phenyl- and heteroaryl-α-hydroxymethanephosphonates were deprotonated to generate carbanions, which enter the Vicarious Nucleophilic Substitution (VNS) of hydrogen in aromatic nitro compounds to form 4-nitrobenzhydrylphosphonates and α-heteroaryl-4-nitrobenzylphosphonates. Similarly acetals of cyanohydrins of heteroaromatic aldehydes (furfural and 2-formylthiophene) react to form heteroaryl 4-nitroarylacetonitriles. The anion of the hemiacetal of acetaldehyde is an efficient leaving group in the base-induced β-elimination step – the crucial step in the VNS reaction. The reaction selectively occurred at the para-position to the nitro group.
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α chlorobenzylation of nitroarenes via Vicarious Nucleophilic Substitution with benzylidene dichloride umpolung of the friedel crafts reaction
Journal of Organic Chemistry, 2018Co-Authors: Jakub Brześkiewicz, Rafal Loska, Mieczyslaw MąkoszaAbstract:Readily available α,α-dichlorotoluenes enter a Vicarious Nucleophilic Substitution (VNS) reaction with electron-deficient arenes to give α-chlorobenzylated nitrobenzenes, as well as six- and five-membered heterocycles. Oxidation of the initially formed α-chlorobenzylic carbanions instead of protonation results in formation of diaryl ketones, providing a means for overall Nucleophilic C–H benzoylation of electron-deficient aromatic rings. Alternatively, benzoylated nitroarenes can be obtained via the reaction of isolated α-chlorodiarylmethanes with sodium azide.
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synthesis of α fluoro α nitroarylacetates via Vicarious Nucleophilic Substitution of hydrogen
Journal of Organic Chemistry, 2016Co-Authors: Justyna Czabanjoźwiak, Rafal Loska, Mieczyslaw MąkoszaAbstract:Readily available ethyl chlorofluoroacetate, when treated with a strong base, forms an α-chloro-α-fluorocarbanion that adds to nitroarenes at a position ortho or para to the nitro group with formation of anionic σH adducts. Subsequent base-induced β-elimination of HCl proceeds selectively to give nitrobenzylic α-fluorocarbanions and, upon protonation, ethyl α-fluoro-α-nitroarylacetates.
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one pot synthesis of oxiranes through Vicarious Nucleophilic Substitution vns darzens reaction
Synlett, 2016Co-Authors: Arkadiusz Sakowicz, Rafal Loska, Mieczyslaw MąkoszaAbstract:Oxiranes are formed in a highly diastereoselective one-pot process, in which aldehydes react with α-chloronitrobenzylic carbanions produced in the Vicarious Nucleophilic Substitution (VNS) reaction of nitroarenes with tert -butyl dichloroacetate.
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one pot synthesis of esters of cyclopropane carboxylic acids via tandem Vicarious Nucleophilic Substitution michael addition process
Journal of Organic Chemistry, 2015Co-Authors: Mieczyslaw Mąkosza, Karol Bester, Piotr CmochAbstract:α-Chlorocarbanions generated via base-induced Vicarious Nucleophilic Substitution reaction of alkyl dichloroacetates with nitroarenes react with Michael acceptors to give esters of cyclopropane carboxylic acids substituted with p-nitroaromatic rings.
Schmidt R.d. - One of the best experts on this subject based on the ideXlab platform.
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New Synthesis of TATB. Scaleup and Product Characterization
Lawrence Livermore National Laboratory, 2000Co-Authors: Schmidt R.d., Pagoria P.f., Mitchell A.r., Lee G.s., Quinlan W.t., Thorpe R., Cates M.Abstract:At the 29th International Annual Conference of ICT (1998), the authors described the results of laboratory-scale process development studies for a new synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). This new synthesis approach--which uses Vicarious Nucleophilic Substitution (VNS) methodology--converts picramide to TATB in high yield, and potentially at lower cost and with few environmental effects than existing synthetic approaches. In this report they describe results of their work on producing TATB by the VNS method at the pilot plant scale. They will discuss structure and control of impurities, changes in yield/quality with reaction conditions, choice of solvents, workup and product isolation, safety, and environmental considerations. Product characterization (particle size, DSC, HPLC, etc.) as well as small-scale safety and performance testing is also discussed
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A new synthesis of TATB using inexpensive starting materials and mild reaction conditions
Lawrence Livermore National Laboratory, 1996Co-Authors: Mitchell A.r., Pagoria P.f., Schmidt R.d.Abstract:TATB is currently manufactured in US by nitration of the expensive TCB to give 2,4,6-trichloro-1,3,5-trinitrobenzene which is then aminated to yield TATB. Elevated temperatures (150 C) are required for both reactions. There is a need for a more economical synthesis of TATB that also addresses current environmental issues. We have recently found that 1,1,1-trimethylhydrazinium iodide (TMHI) allows the amination of nitroarenes at ambient temperature via Vicarious Nucleophilic Substitution of hydrogen. TMHI reacts with picramide in presence of strong base (NaOMe or t-BuOK) to give TATB in over 95% yield. TMHI and picramide can be obtained from either inexpensive starting materials or surplus energetic materials from demilitarization activities, such as the 30,000 metric tons of UDMH (surplus rocket propellant) from the former Soviet Union
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Conversion of the rocket propellant UDMH to a reagent useful in Vicarious Nucleophilic Substitution reactions
Lawrence Livermore National Laboratory, 1995Co-Authors: Mitchell A.r., Pagoria P.f., Schmidt R.d.Abstract:The objective of our program is to develop novel, innovative solutions for the disposal of surplus energetic materials resulting from the demilitarization of conventional and nuclear munitions. In this report we describe the use of surplus propellant (UDMH) and explosives (TNT, Explosive D) as chemical precursors for higher value products. The conversion of UDMH to 1,1,1-trimethylhydrazinium iodide (TMHI) provides a new aminating reagent for use in Vicarious Nucleophilic Substitution (VNS) reactions. When TMHI is reacted with various nitroarenes the amino functionality is introduced in good to excellent yields. Thus, 2,4,6-trinitroaniline (picramide) reacts with TMHI to give 1,3,5-triamino-2,4,6-trinitroaniline (TATB) while 2,4,6-trinitrotoluene (TNT) reacts with TMHI to give 3,5-diamino-2,4,6-trinitrotoluene (DATNT). The advantages, scope and limitations of the VNS approach and the use of TMHI are discussed
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Vicarious amination of nitroarenes with trimethylhydrazinium iodine
Lawrence Livermore National Laboratory, 1995Co-Authors: Pagoria P.f., Schmidt R.d., Mitchell A.r.Abstract:This paper investigated the use of 1,1,1-trimethylhydrazinium iodide as a Vicarious Nucleophilic Substitution reagent for introducing amino groups into nitroaromatic substrates. The substrates included nitroarenes, polynitrobenzenes, picramide, TNB,TNT, and dinitropyrazole; other nitroazoles are being studied
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New aminating reagents forthe synthesis of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB) and other insensitive energetic materials
Lawrence Livermore National Laboratory, 1995Co-Authors: Pagoria P.f., Mitchell A.r., Schmidt R.d.Abstract:We are investigating the amination of electrophilic aromatic systems through the use of Vicarious Nucleophilic Substitution (VNS) chemistry. This research has led to a new synthesis of 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) and 1,3-diamino-2,4,6-trinitrobenzene (DATB) which uses 2,4,6-trinitroaniline (picramide) or 1,3,5-trinitrobenzene as starting materials. We also describe the development of a new class of VNS aminating reagents based on quarternary hydrazinium halides. 1,1,1-Trimethylhydrazinium iodide (TMHI), available from the methylation of the surplus propellant uns-dimethylhydrazine (UDMH), was used in a new synthesis of TATB. The advantages, scope and limitations of the VNS approach to the synthesis of TATB and other amino-substituted nitroarenes are discussed
Krzysztof Wojciechowski - One of the best experts on this subject based on the ideXlab platform.
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simple synthesis of dimethyl nitrobenzhydrylphosphonates and heteroarylnitroarylacetonitriles via Vicarious Nucleophilic Substitution vns reaction
Synthesis, 2020Co-Authors: Mieczyslaw Mąkosza, Malgorzata Bechcicka, Krzysztof WojciechowskiAbstract:Acetals of dimethyl phenyl- and heteroaryl-α-hydroxymethanephosphonates were deprotonated to generate carbanions, which enter the Vicarious Nucleophilic Substitution (VNS) of hydrogen in aromatic nitro compounds to form 4-nitrobenzhydrylphosphonates and α-heteroaryl-4-nitrobenzylphosphonates. Similarly acetals of cyanohydrins of heteroaromatic aldehydes (furfural and 2-formylthiophene) react to form heteroaryl 4-nitroarylacetonitriles. The anion of the hemiacetal of acetaldehyde is an efficient leaving group in the base-induced β-elimination step – the crucial step in the VNS reaction. The reaction selectively occurred at the para-position to the nitro group.
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application of Vicarious Nucleophilic Substitution in organic synthesis
Liebigs Annalen, 1997Co-Authors: Mieczyslaw Makosza, Krzysztof WojciechowskiAbstract:Vicarious Nucleophilic Substitution (VNS) provides the possibility of the replacement of hydrogen atoms in electrophilic arenes with α-functionalized alkyl substituents. This review focuses on the transformations of products obtained by VNS, particularly into heterocyclic compounds. In addition, some characteristic features of the VNS mechanism are briefly described.
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Vicarious Nucleophilic Substitution vns of hydrogen in azulenes
European Journal of Organic Chemistry, 1994Co-Authors: Mieczyslaw Magoikosza, Renata Kuciak, Krzysztof WojciechowskiAbstract:Azulene reacts with carbanions bearing a leaving group according to the Vicarious Nucleophilic Substitution (VNS) scheme. Treatment of 6-chloroazulene with such carbanions affords the VNS reaction and Nucleophilic aromatic Substitution (SNAr) products.
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synthesis of benzosultams via intramolecular Vicarious Nucleophilic Substitution of hydrogen
Synthesis, 1992Co-Authors: Krzysztof Wojciechowski, Mieczyslaw MakoszaAbstract:Intramolecular Vicarious Nucleophilic Substitution of Hydrogen (VNS) in N-(3-nitrophenyl)- and N-(3-nitrobenzyl) chloromethylsulfonamides leads to five-, six- and seven-membered benzosultam derivatives
A Rykowski - One of the best experts on this subject based on the ideXlab platform.
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tandem Vicarious Nucleophilic Substitution of hydrogen intramolecular diels alder reaction of 1 2 4 triazines into functionalized cycloalkenopyridines
Chemical & Pharmaceutical Bulletin, 2002Co-Authors: Danuta Branowska, Stanislaw Ostrowski, A RykowskiAbstract:Synthesis of 2,3- and 3,4-cyclopentenopyridines, 5,6,7,8-tetrahydroquinolines and 5,6,7,8-tetrahydroisoquinolines from 1,2,4-triazine derivatives is reported. Introduction of an α-functionalized methyl substituent (e.g. arylsulphonyl, sulphonamide, sulphonic acid ester) into position 3- or 6- of triazines by Vicarious Nucleophilic Substitution of hydrogen and subsequent alkylation with alkyl iodides bearing an acetylenic function in terminal position afforded valuable intermediates for intramolecular Diels–Alder reaction with inverse electron demand. When heated at higher temperature, these triazine derivatives gave the Diels–Alder cycloadducts, which, after spontaneous extrusion of nitrogen moiety, led to a variety of functionalized cycloalkenopyridine derivatives.
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Vicarious Nucleophilic Substitution of hydrogen in pyridazines
Tetrahedron Letters, 1992Co-Authors: Andrzej Ostrowicz, Mieczyslaw Makosza, Sylwester Baloniak, A RykowskiAbstract:Abstract Pyridazines, 3-pyridazinones and 3,6-pyridazinediones readily undergo Vicarious Nucleophilic Substitution of hydrogen (VNS) with carbanion of chloromethyl p-tolyl sulfone to form new carbon-carbon bonds. The reaction offers a novel approach to the synthesis of functionalized pyridazine derivatives.
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reactions of organic anions 177 Vicarious Nucleophilic Substitution of hydrogen bisannulation and competitive reactions of α haloalkyl carbanions with bicyclic azaaromatic compounds
Chemische Berichte, 1991Co-Authors: Mieczyslaw Makosza, J. Golinski, Stanislaw Ostrowski, Arvind B Sahasrabudhe, A RykowskiAbstract:Carbanions of α-haloalkyl aryl sulfones, sulfonates, and sulfonamides react with bicyclic heteroaromatic compounds (quinoxalines, naphthyridines, and 5-azaquinoxalines) according to two general pathways: Vicarious Nucleophilic Substitution of hydrogen and/or bisannulation. In some cases other competitive reactions such as S N Ar are observed. Factors governing the direction of these reactions are discussed in terms of the charge distribution in the anionic σ adducts and the reaction conditions
