- N,O-diacylhydroxylamines - Structures in crystals and solutions
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The structures of four N,O-diacylhydroxylamines (RCOHNOCOR′, R, R′ = Me, Ph) were determined in the solid state by X-ray diffraction and studied by NMR and IR spectroscopies in solution. The interpretation of the results was supported by ab-initio calcula
- Schraml, Jan,Sykora, Jan,Fiedler, Pavel,Roithova, Jana,Mindl, Jaromir,Blechta, Vratislav,Cisarova, Ivana,Exner, Otto
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- Synthesis of sulfimides and N-Allyl-N-(thio)amides by Ru(II)catalyzed nitrene transfer reactions of N-acyloxyamides
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The N-acyloxyamides were employed as effective N-acyl nitrene precursors in reactions with thioethers under the catalysis of a commercially available Ru(II) complex, from which a variety of sulfimides were synthesized efficiently and mildly. If an allyl group is contained in the thioether precursor, the [2,3]-sigmatropic rearrangement of the sulfimide occurs simultaneously and the N-allyl-N-(thio)amides were obtained as the final products. Preliminary mechanistic studies indicated that the Ru-nitrenoid species should be a key intermediate in the transformation.
- Zhang, Xinyu,Lin, Bo,Chen, Jianhui,Chen, Jiajia,Luo, Yanshu,Xia, Yuanzhi
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p. 819 - 825
(2021/02/01)
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- Facile synthesis ofO-acylhydroxamatesviareaction of oxime chlorides with carboxylic acids
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A simple and efficient method for the synthesis ofO-acylhydroxamate derivatives from oxime chlorides and carboxylic acids was developed. The reaction affords clean and facile access to diverseO-acylhydroxamates in high yields (up to 85%). The chemical structure of a typical product was confirmed using single-crystal X-ray structure analysis.
- Chen, Rongxiang,Li, Yan-Li,Sun, Aili,Wang, Kai-Kai,Zhang, Shan-Shan,Zhao, Ying-Chao
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p. 40193 - 40196
(2021/12/31)
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- NiH-Catalyzed Proximal-Selective Hydroamination of Unactivated Alkenes
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Reported herein is a modular, NiH-catalyzed system capable of proximal-selective hydroamination of unactivated alkenes with diverse amine sources. The key to the successful implementation of this approach is the promotion of NiH insertion into even highly substituted olefins via coordination of the bidentate directing group to the nickel complex. A wide range of primary and secondary amines can be installed in both internal and terminal unactivated alkenes with excellent regiocontrol under the optimized reaction conditions. This protocol is flexible and general for the preparation of a variety of valuable β- and γ-amino acid building blocks that would otherwise be difficult to synthesize. The utility of this transformation was further demonstrated by the site-selective late-stage modification of complex and medicinally relevant molecules. Combined experimental and computational studies illuminate the detailed reaction mechanism.
- Jeon, Jinwon,Lee, Changseok,Seo, Huiyeong,Hong, Sungwoo
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supporting information
p. 20470 - 20480
(2020/11/27)
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- The Easy Approach to N -Hydroxy- N -cycloalkenylamides through Nitrosocarbonyl Ene Reactions to Cycloalkenes: Valuable Compounds for Antiviral Syntheses
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An easy approach to N -hydroxy- N -cycloalkenylamides, ene adducts of cyclic alkenes of different sizes, is presented. The products can be obtained both through the thermal generation of the nitrosocarbonyl intermediates and via the photochemical fragment
- Hameed, Karzan Khaleel,Amin, Ahmed Anwar,Hussain, Faiq H. S.,Memeo, Misal Giuseppe,Moiola, Mattia,Quadrelli, Paolo
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p. 1383 - 1390
(2019/03/08)
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- Direct Observation of Acyl Nitroso Compounds in Aqueous Solution and the Kinetics of Their Reactions with Amines, Thiols, and Hydroxamic Acids
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Acyl nitroso compounds or nitrosocarhonyls (RC(O)N=O) are reactive short-lived electrophiles, and their hydrolysis and reactions with nucleophiles produce HNO. Previously, direct detection of acyl nitroso species in nonaqueous media has been provided by time-resolved infrared spectroscopy demonstrating that its half-life is about 1 ms. In the present study hydroxamic acids (RC(O)NHOH) are oxidized electrochemically in buffered aqueous solutions (pH 5.9-10.2) yielding transient species characterized by their maximal absorption at 314-330 nm. These transient species decompose via a first-order reaction yielding mainly HNO and the respective carboxylic acid and therefore are ascribed to RC(O)N=O. The sufficiently long half-life of RC(O)N=O in aqueous solution allows for the first time the study of the kinetics of its reactions with various nucleophiles demonstrating that the nucleophilic reactivity follows the order thiolate > hydroxamate > amine. Metal chelates of CH3C(O)NHOH catalyze the hydrolysis of CH3C(O)N=O at the efficacy order of CuII > ZnII > NiII > CoII where only CuII catalyzes the hydrolysis also in the absence of the hydroxamate. Finally, oxidation of hydroxamic acids generates HNO, and the rate of this process is determined by the half-life of the respective acyl nitroso compound.
- Maimon, Eric,Lerner, Ana,Samuni, Amram,Goldstein, Sara
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p. 7006 - 7013
(2018/09/06)
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- O-nucleophilicity of hydroxamate ions for cleavage of carboxylate and phosphate esters in cationic micelles
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The nucleophilic reactivities of hydroxamate (HA-) ions of the structure RCONHO- [R = CH3 (acetohydroxamate, AHA -), C6H5 (benzohydroxamate, BHA-), 2-OHC6H4
- Satnami, Manmohan L.,Karbhal, Indrapal,Dewangan, Hitesh K.
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supporting information
p. 419 - 432
(2014/07/08)
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- Lossen rearrangements under heck reaction conditions
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The classical Lossen rearrangement converts activated hydroxamic acids to isocyanates that form numerous products upon their reaction with nucleophiles. We report a simple and highly efficient method of using Heck reaction conditions to initiate Lossen rearrangements of hydroxamic acids. In addition, Lossen rearrangements occur in the presence of palladium(II) acetate or triethylamine, components of the Heck reaction, alone. A potential mechanism is provided to explain this reactivity and these results show that Heck reactions and Lossen rearrangements occur under the same conditions and may provide new methods for facile initiation of Lossen rearrangements.
- AbdelHafez, El-Shimaa M.N.,Aly, Omar M.,Abuo-Rahma, Gamal El-Din A.A.,King, S. Bruce
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supporting information
p. 3456 - 3464
(2015/02/05)
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- Rhodium(III)-catalyzed heterocycle synthesis using an internal oxidant: Improved reactivity and mechanistic studies
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Directing groups that can act as internal oxidants have recently been shown to be beneficial in metal-catalyzed heterocycle syntheses that undergo C-H functionalization. Pursuant to the rhodium(III)-catalyzed redox-neutral isoquinolone synthesis that we recently reported, we present in this article the development of a more reactive internal oxidant/directing group that can promote the formation of a wide variety of isoquinolones at room temperature while employing low catalyst loadings (0.5 mol %). In contrast to previously reported oxidative rhodium(III)-catalyzed heterocycle syntheses, the new conditions allow for the first time the use of terminal alkynes. Also, it is shown that the use of alkenes, including ethylene, instead of alkynes leads to the room temperature formation of 3,4-dihydroisoquinolones. Mechanistic investigations of this new system point to a change in the turnover limiting step of the catalytic cycle relative to the previously reported conditions. Concerted metalation-deprotonation (CMD) is now proposed to be the turnover limiting step. In addition, DFT calculations conducted on this system agree with a stepwise C-N bond reductive elimination/N-O bond oxidative addition mechanism to afford the desired heterocycle. Concepts highlighted by the calculations were found to be consistent with experimental results.
- Guimond, Nicolas,Gorelsky, Serge I.,Fagnou, Keith
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supporting information; experimental part
p. 6449 - 6457
(2011/06/16)
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- First O-glycosylation of hydroxamic acids
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(Chemical Equation Presented) The first O-glycosylation of hydroxamic acids is reported. This process involves the use of glycosyl N-phenyl trifluoroacetimidates as glycosyl donors in the presence TMSOTf and 4 A molecular sieves in dichloromethane. Under
- Thomas, Mickael,Gesson, Jean-Pierre,Papot, Sebastien
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p. 4262 - 4264
(2008/02/05)
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- Regio-selective formation of O-acyl/O-benzoyl hydroxamates by using a polymer supported reagent strategy
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Rapid, quantitative and regioselective O-acylation/O-benzoylation of hydroxamic acids has been carried using polymer supported hydroxamate anions and acetyl/benzoyl chloride under mild conditions. The isolation of unambiguous and pure products by si-mple
- Burungule,Bondge,Munde,Bhingolikar,Mane
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p. 1923 - 1927
(2007/10/03)
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- HSV primase inhibitors
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The invention provides compounds of the formula 1 that are active against the HSV primase enzyme: whereinR1 is hydroxy or amino;R2 is hydrogen, halo, (C1-4)alkyl or (C1-4)alkoxy; R3 is hydrogen, halo,
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- The mild oxidation of nitrile oxides affords a convenient entry to nitrosocarbonyl intermediates, versatile tools in organic syntheses
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Nitrile oxides are oxidized by tertiary amine N-oxides in different solvents at room temperature to afford in the presence of dienes nitrosocarbonyl adducts in fair yields. The mild conditions used in oxidizing a variety of nitrile oxides promise a wide application of this method in synthetic processes.
- Quadrelli,Mella,Gamba Invernizzi,Caramella
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p. 10497 - 10510
(2007/10/03)
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- PREPARATION AND CHARACTERIZATION OF MIXED ANHYDRIDES OF O-ACYLARYLCARBOHYDROXIMIC ACID
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A number of N,O-diacylhydroxylamines have been prepared by the reaction of potassium salts of hydroxamic acids with a variety of acylating agents which include: benzoyl, p-nitrobenzoyl, anisoyl, p-chlorobenzoyl and lauroyl chlorides in dioxane under reflu
- Sharma, Rajinder P.,Sharma, Kusum,Lakhanpal, Sunita,Sharma, Namita,Misra, Bhupendra N.
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p. 2150 - 2158
(2007/10/02)
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- Insecticidal and Herbicidal Activity of Some Hydroxamic and Dihydroxamic Acid Derivatives
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A number of hydroxamic and dihydroxamic acid derivatives have been prepared and their insecticidal and herbicidal activities determined.
- Sharma, R. P.,Sharma, Namita,Misra, B. N.
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p. 1159 - 1161
(2007/10/02)
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- Triphenylmethyl Phenylcyanomethylenenitronate: Formation and Thermolysis
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The previously reported formation of carbon dioxide, α,α'-bis(tritylazo)stilbene (4), benzonitrile N-oxide (5), trityl isocyanate (6), and C33H25N3O (11) from a mixture ot trityl chloride and silver phenylcyanomethylenenitronate in toluene is now attributed to the initial formation at -20 deg C of trityl phenylcyanomethylenenitronate (3) and its dissociations at 5 deg C.The ester (3) was characterized by conversion into bromonitrophenylacetonitrile (7) by treatment with bromine, to p-nitrobenzoyl cyanide (8) by treatment with dinitrogen tetraoxide, to trityl alcohol by hydrolysis, and to a mixture of trityl alcohol and trityl peroxide by exposure to the atmosphere.The bisazostilbene (4) (18percent) and C33H25N3O, identified by X-ray crystallographic analysis to be 4,5-diphenyl-1-triphenylmethoxy-1,2,3-triazole (11) (24percent), were obtained from the nitronate ester (3) in toluene at 5 deg C; the nitrile oxide (5) and the isocyanate (6) were obtained in low yields from the ester (3) in dimethyl sulphoxide at 25 deg C.Hydrolysis converted the triazole (11) into 1-hydroxy-4,5-diphenyl-1,2,3-triazole (12) and trityl alcohol.Silver p-bromophenylcyanomethylenenitronate and trityl chloride afforded α,α'-bis-(tritylazo)-p,p'-dibromostilbene and its thermolysis product, p,p'-dibromodiphenylacetylene.Fragmentation of the ester (3) in presence of added phenyl isocyanate gave the bisazo compound (4) and 3,4-diphenyl-1,2,4-oxodiazol-5-one (18).A similar mixture stored at -20 deg C gave the triazole (11) and the oxadiazolone (18).Aroyl nitrile oxides as well as phenyl isocyanate suppressed the formation of the red bisazostilbene (4).The intermediacy of the N-trityl imine (14) of 4H-3-phenyl-1,2-oxazet-4-one-2-oxide in the thermolysis of the nitronate (3) was discussed.
- Boyer, Joseph H.,Manimaran, Thankiavelu,Ramakrishnan, Vayalakkavoor T.
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p. 2163 - 2170
(2007/10/02)
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- Preparation of Some Dihydroxamic Acids and Their Reaction with Benzenesulphonyl Chloride
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Several dihydroxamic acids (II) have been prepared and reacted with benzenesulphonyl chloride in dioxane below 10 deg C in the presence of triethylamine to yield the corresponding imino-ether type of compounds (III).The structure elucidation of II and III
- Misra, B. N.,Sharma, R. P.,Diksha
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p. 1182 - 1183
(2007/10/02)
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- REACTIONS OF TRANSIENT C-NITROSOCARBONYL COMPOUNDS WITH DIENES, MONOOLEFINS, AND NUCLEOPHILES
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Nitrosocarbonylbenzene and nitrosocarbonylmethane, formed as transient intermediates by oxidation of benzo- and aceto-hydroxamic acid, respectively, with tetraethylammonium periodate, are trapped by cyclopentadiene to give the corresponding cycloadducts (5).The adduct (5; R=Ph) dissociates in solution at 80 deg C to reform nitrosocarbonylbenzene, which reacts with thebaine (1) to give (4; R=Ph) and with triphenylphosphine to give phenyl isocyanate.Cycloadducts of nitrosocarbonylbenzene with cyclohexa-1,3-diene (6) and with cyclo-octatetraene (7) have also been prepared.The adduct (3; R=Ph) of nitrosocarbonylbenzene and 9,10-dimethylanthracene, when heated with 1-allyl-3,4-methylenedioxybenzene, oct-1-ene, or 2,5-dimethylhexa-2,4-diene, gives the corresponding 'ene' reaction products of the olefins and nitrosocarbonylbenzene.When heated alone, the adduct (3; R=Ph) gives 9,10-dimethylanthracene, benzoic anhydride, and nitrous oxide.Oxidation of 2,4,6-trimethylbenzohydroxamic acid in the presence of thebaine gives the adduct (4; R=2,4,6-trimethylphenyl).However, 2,4,6-trimethylnitrosocarbonylbenzene is insufficiently stable to be isolated; in the absence of a diene it decomposes to give 2,4,6-trimethylbenzoic anhydride as the major product.
- Corrie, John E.T.,Kirby, Gordon W.,Mackinnon, John W.M.
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p. 883 - 886
(2007/10/02)
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- Action de l'anhydride acetique et des chlorures de benzoyle et de p-toluene sulfonyle sur des nitrones derivees de ceto-17 steroides. Conditions conduisant a un rearrangement ou a une fonctionnalisation
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The reaction of the title reagents under anhydrous conditions and in the presence of base leads to steroidal derivatives functionalised at position 16; whereas, in the presence of water, paratoluenesulphonyl chloride gives 17-aza-D-homo lactams by ring expansion, and use of benzoyl chloride promotes a hydrolytic fragmentation.In contrast to earlier studies, the formation of an oxaziridine under aqueous alkaline conditions was not observed in this work.These results, when considered in conjunction with those previously obtained, enable the course of these reactions to be determined as a function of the reaction conditions.
- Cherest, M.,Lusinchi, X.
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p. 227 - 232
(2007/10/02)
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- 1H-1,2,4-Triazole 2-oxide from O-benzoyl derivatives of N-Substituted benzamidoximes and benzonitrile oxide
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Treatment of the readily prepared O-benzoyl derivatives of N-substituted benzamidoximes with benzonitrile oxide gave 1H-1,2,4-triazole 2-oxides.
- Foti, Francesco,Grassi, Giovanni,Risitano, Francesco,Caruso, Francesco
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p. 3048 - 3054
(2007/10/02)
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- Formation and Dienophilic Reactions of Transient C-Nitrosocarbonyl Compounds
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Oxidation of benzohydroxamic acid with tetraethylammonium periodate in the presence of the conjugated diene thebaine (1) gave the cycloadduct 6β,14β-(N-benzoylepoxyimino)-6,14-dihydrothebaine (2; R = Ph), in high yield.The corresponding N-acetyl derivative (2; R = Me) was prepared similarly using acetoxyhydroxamic acid.Likewise, 2-benzoyl- and 2-acetyl-3,6-dihydro-2H-1,2-oxazine (5; R = Ph) and (5; R = Me) were obtained from buta-1,3-diene, and the N-benzoyl and N-acetyl derivatives of 9,10-epoxyimino-9,10-dihydro-9,10-dimethylanthracene (6; R = PhCO) and (6; R = Ac) from 9,10-dimethylanthracene (DMA).These reactions are believed to involve the formation of nitrosocarbonylbenzene or nitrosocarbonylmethane, representatives of a new class of transient, reactive species.The cycloadduct (6; R = Ac) decomposed in benzene at 60 deg C in the presence of thebaine (1) to give the thebaine adduct (2; R = Me) and DMA.First-order kinetics were observed for the release of DMA, consistent with slow dissociation of the adduct (6; R = Ac) followed by rapid capture of nitrosocarbonylmethane by thebaine.The related adduct (6; R = PhCO) behaved similarly.DMA adducts of the type (6) are valuable in studies on the reactions of nitrosocarbonyl compounds, especially with co-reactants sensitive to oxidation.Thus (6; R = Ac) and 1,3-diphenylisobenzofuran (7) reacted cleanly in benzene at 80 deg C to give the O-acetyloxime (10) of 1,2-dibenzoylbenzene, possibly via the N-acetylnitrone (9) derived from the initially formed cycloadduct (8).
- Kirby, Gordon W.,Sweeny, James G.
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p. 3250 - 3254
(2007/10/02)
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