- Stability of electron deficient activated nitronates under neutral and Lewis acid catalyzed conditions. Facile nitronate cycloaddition reactions to the magnesium alkoxides of allylic alcohols leading to isoxazolidines and isoxazolines
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N-Methoxy-N-[bis(methoxycarbonyl)methylene]amine N-oxide and N-methoxy- N-(methoxycarbonylmethylene)amine N-oxide as electron-deficient activated nitronates, show an exceptionally high reactivity to the magnesium alkoxides of allylic alcohols. Isoxazolidines or isoxazolines are formed as cycloadducts, depending upon the substitution pattern of the allylic alcohols. When the latter C-monosubstituted nitronate is treated with a catalytic amount of boron trifluoride etherate, the corresponding nitrile oxide is smoothly generated through β-elimination of methanol.
- Kanemasa, Shuji,Kaga, Shinsuke,Wada, Eiji
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- Dimethylmalonato zinc complexes as molecular precursors for electronic grade zinc oxide: Towards a systematic ligand design by understanding molecular decomposition mechanisms
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Zinc complexes with dimethyl 2-hydroxyimino- and 2-nitromalonate (dmm-NOH and Hdmm-NO2, respectively) were synthesized and examined as potential precursors for nanocrystalline zinc oxide. The functionalised 1,3-diketones are sufficiently acidic to allow direct synthesis from hydrozincite or zinc 2-propoxide as well as their full spectroscopic and analytical characterization. Their nominal elemental compositions of [Zn 4O(dmm-NO)6] and [Zn3(OH)4(dmm- NO2)2] suggest the presence of multinuclear cage structures with oxo- or hydroxo-bridging ligands. This assumption is in accordance with the obtained spectroscopic data. Thermogravimetry coupled with mass spectrometry and infrared spectroscopy (TG/MS and TG-IR) indicate the formation of dimethylcarbonate and methanol during the decomposition. Both precursors exhibit good film formation properties and the obtained zinc oxide was further characterized by XRD, SEM, TEM and PL. Finally, the semiconducting electronic behaviour of the obtained nanocrystalline ZnO was studied in a field-effect transistor (FET) device. Copyright
- Hoffmann, Rudolf C.,Schneider, J?rg J.
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- Atropisomerism in monopyrroles
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As observed by NMR, iodopyrroles 1a and 1b (ethyl and methyl 3,5-dimethyl-4-[(1′-iodo-2′,2′-dimethyl)propyl]pyrrole-2- carboxylate) and a variety of related derivatives with iodine replaced by methoxy 2, thiomethyl 3, acetic acid esters 4, propionic acid ester 5 or malonic esters 6 exhibit restricted rotation about the C(4)-C(1′) bond due to the bulky tert-butyl group and an ortho effect from the sterically crowded 3,5-dimethylpyrrole. Most of the compounds, which are members of the rare class of atropisomers due to restricted rotation about an sp3-sp2 C-C bond, undergo diastereomeric enrichment by preparative TLC and crystallization. From dynamic NMR studies of the enriched diastereomers one can determine kinetic and thermodynamic parameters associated with the atropisomerism, e.g., ΔG? ~24 kcal/mol for 1 and 5 (313 K), ~22 kcal/mol for 3 (273 K), and ~25 kcal/mol for 6 (313 K) in C2D2Cl4 solvent.
- Boiadjiev, Stefan E.,Lightner, David A.
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- Reaction of diaziridine-3,3-dicarboxylic acid dihydrazide with acetone
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Using the reaction of diaziridine-3,3-dicarboxylic acid dihydrazide with acetone, new bicyclic diaziridines 7a,b have been obtained instead of expected tricyclic heterocycle 8.
- Strumfs, Boriss,Liepin'sh, Edvards,Belyakov, Sergey,Trapencieris, Peteris,Kostyanovsky, Remir G.
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- An enantiomerically pure bilirubin. Absolute configuration of (αR,α′R)-dimethylmesobilirubin-XIIIα
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Enantiomerically pure (+)-(αR,α′R)-dimethylmesobilirubin-XIIIα 1 and its (αS,α′S) enantiomer ent-1 were synthesized in ten steps from simple precursors. Resolution was achieved at an early stage in the synthesis, with a racemic monopyrrole precursor rac-6 being converted to its amides 8 with (1S)-camphor-2,10-sultam. Resolution of 8 to 99% d.e. was accomplished in three crystallizations, and the absolute configuration of the acid 6 was deduced by X-ray crystallography of the more crystalline, diastereomerically pure amide 7. Circular dichroism spectroscopy of 1 showed intense bisignate Cotton effects: Δε435max = +344, Δε391max = -193 (CHCl3), as expected for a molecular exciton, and consistent with a P-helical intramolecularly hydrogen-bonded ridge-tile conformation. The Cotton effect magnitudes of 1 match almost exactly those found for (-)-(βS,β′S)-dimethylmesobilirubin-XIIIα 11 and (+)-(αR,β′R)-dimethylmesobilirubin-XIIIα. However, the Cotton effect of the pseudo-meso diastereomer (αR,β′S)-dimethylmesobilirubin-XIIIα 12 is not zero. Its large positive exciton couplet and 1H NMR NOE analysis confirm that an α-CH3 exerts a greater steric demand than a β-CH3 - by a factor of ~3.
- Boiadjiev, Stefan E.,Lightner, David A.
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- ANTIVIRAL 1,3-DI-OXO-INDENE COMPOUNDS
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The invention provides compounds of Formula (I): as described herein, along with pharmaceutically acceptable salts, pharmaceutical compositions containing such compounds, and methods to use these compounds, salts and compositions for treating viral infections.
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Paragraph 0414
(2021/10/22)
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- Unified Strategy to Amphenicol Antibiotics: Asymmetric Synthesis of (-)-Chloramphenicol, (-)-Azidamphenicol, and (+)-Thiamphenicol and Its (+)-3-Floride
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The asymmetric synthesis of (-)-chloramphenicol, (-)-azidamphenicol, and (+)-thiamphenicol and its (+)-3-floride, (+)-florfenicol, is reported. This approach toward the amphenicol antibiotic family features two key steps: (1) a cinchona alkaloid derived urea-catalyzed aldol reaction allows highly enantioselective access to oxazolidinone gem-diesters and (2) a continuous flow diastereoselective decarboxylation of thermally stable oxazolidinone gem-diesters to form the desired trans-oxazolidinone monoesters with two adjacent stereocenters that provide the desired privileged scaffolds of syn-vicinal amino alcohols in the amphenicol family.
- Liu, Jinxin,Li, Yaling,Ke, Miaolin,Liu, Minjie,Zhan, Pingping,Xiao, You-Cai,Chen, Fener
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p. 15360 - 15367
(2020/11/30)
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- Copper-Catalyzed Carbonyl Group Controlled Coupling of Isatin Oximes with Arylboronic Acids To Prepare N-Aryloxindole Nitrones
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A variety of (E)-N-aryloxindole nitrones were prepared in good to excellent yields by using a copper-catalyzed coupling reaction of isatin oximes and arylboronic acids under mild conditions. Various arylboronic acids that contain sensitive functional groups were tolerated in the transformation, and detailed studies show that the carbonyl group of the isatin oximes serves as a ligand to control the formation of the (E)-oxindole nitrones. This method to prepare (E)-N-aryloxindole nitrones was easily performed on a gram scale and efficiently used to synthesize estrone-derived oxindole nitrone in high yield.
- Mo, Xue-Ling,Chen, Chun-Hua,Liang, Cui,Mo, Dong-Liang
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p. 150 - 159
(2017/11/28)
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- PREPARATION OF SECONDARY AMINES WITH ELECTROPHILIC N-LINCHPIN REAGENTS
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In one aspect, the present disclosure provides methods of preparing a secondary amine. In some embodiments, the secondary amine comprises two different groups or two identifical groups. Also provided herein are compositions for use in the preparation of the secondary amine.
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Page/Page column 54
(2018/12/13)
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- Synthesis of N-Aryl Oxindole Nitrones through a Metal-Free Selective N-Arylation Process
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An efficient selective N-arylation of 3-(hydroxyimino)indolin-2-ones with diaryliodonium salts to prepare (Z)-N-aryl oxindole nitrones has been achieved under simple base-mediated conditions. The reaction tolerated a variety of diaryliodonium salts with diverse and sensitive functional groups. Studies on the oxime structures revealed that the pyrroline ring and carbonyl group in 3-(hydroxyimino)indolin-2-ones played important roles in the selective N-arylation process. The N-aryl oxindole nitrones could be prepared rapidly and easily at the gram scale.
- Wu, Si-Yi,Ma, Xiao-Pan,Liang, Cui,Mo, Dong-Liang
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p. 3232 - 3238
(2017/03/23)
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- Practical Singly and Doubly Electrophilic Aminating Agents: A New, More Sustainable Platform for Carbon-Nitrogen Bond Formation
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Given the importance of amines in a large number of biologically active natural products, active pharmaceutical ingredients, agrochemicals, and functional materials, the development of efficient C-N bond-forming methods with wide substrate scope continues to be at the frontier of research in synthetic organic chemistry. Here, we present a general and fundamentally new synthetic approach for the direct, transition-metal-free preparation of symmetrical and unsymmetrical diaryl-, arylalkyl-, and dialkylamines that relies on the facile single or double addition of readily available C-nucleophiles to the nitrogen atom of bench-stable electrophilic aminating agents. Practical single and double polarity reversal (i.e., umpolung) of the nitrogen atom is achieved using sterically and electronically tunable ketomalonate-derived imines and oximes. Overall, this novel approach represents an operationally simple, scalable, and environmentally friendly alternative to transition-metal-catalyzed C-N cross-coupling methods that are currently used to access structurally diverse secondary amines.
- Kattamuri, Padmanabha V.,Yin, Jun,Siriwongsup, Surached,Kwon, Doo-Hyun,Ess, Daniel H.,Li, Qun,Li, Guigen,Yousufuddin, Muhammed,Richardson, Paul F.,Sutton, Scott C.,Kürti, László
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supporting information
p. 11184 - 11196
(2017/08/21)
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- THIADIAZOLYL-OXIMINOACETIC ACID DERIVATIVE COMPOUNDS
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Thiadiazolyl-oximinoacetic acid derivatives have been synthesized, which are useful in the manufacture of cephalosporin antibiotic compounds. Compound (1 ) (TATD) is commercially available (CAS No. 76028-96-1 ). It has now been discovered that the thiadiazolyl-oximinoacetic acid derivative compound (1 ) (TATD) can be prepared from dimethyl malonate (SM 1, CAS No. 108-59-8) according to methods described herein. The methods provide products having desirable purity.
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Paragraph 0127-0130
(2016/07/05)
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- METAL PRECURSOR AND METAL PRECURSOR INK USING THE SAME
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Provided are a metal precursor containing an oxime group, which is represented by general formula 1, and a metal precursor ink containing same. The metal precursor ink according to the present invention enhance metal content, induce intramolecular and/or intermolecular complexation, thereby enabling low temperature sintering with excellent solubility and stability. The metal precursor ink according to the present invention can be used to form a metal wire with a desired shape. Therefore, the metal precursor ink can find applications in the field of printed electronics, particularly various electrodes, such as mesh type transparent electrodes.
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Paragraph 0066
(2015/12/07)
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- Dimethylmalonato zinc complexes as molecular precursors for electronic grade zinc oxide: Towards a systematic ligand design by understanding molecular decomposition mechanisms
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Zinc complexes with dimethyl 2-hydroxyimino- and 2-nitromalonate (dmm-NOH and Hdmm-NO2, respectively) were synthesized and examined as potential precursors for nanocrystalline zinc oxide. The functionalised 1,3-diketones are sufficiently acidic to allow direct synthesis from hydrozincite or zinc 2-propoxide as well as their full spectroscopic and analytical characterization. Their nominal elemental compositions of [Zn4O(dmm-NO)6] and [Zn3(OH)4(dmm-NO2)2] suggest the presence of multinuclear cage structures with oxo- or hydroxo-bridging ligands. This assumption is in accordance with the obtained spectroscopic data. Thermogravimetry coupled with mass spectrometry and infrared spectroscopy (TG/MS and TG-IR) indicate the formation of dimethylcarbonate and methanol during the decomposition. Both precursors exhibit good film formation properties and the obtained zinc oxide was further characterized by XRD, SEM, TEM and PL. Finally, the semiconducting electronic behaviour of the obtained nanocrystalline ZnO was studied in a field-effect transistor (FET) device.
- Hoffmann, Rudolf C.,Schneider, J?rg J.
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p. 2241 - 2247
(2015/04/27)
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- Nitrite ionic liquids (IL-ONO and [bmim]NO2) as effective nitrosonium sources for the synthesis of α-oximinoketones under mild heterogeneous conditions
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Ketones and β-diketones were nitrosated and converted to their corresponding α-oximinoketones using task-specific ionic liquids, 1-(4-nitritobutyl)-3-methylimidazolium chloride, IL-ONO, and 1-butyl-3-methylimidazolium nitrite at room temperature. The results from two ionic liquids are comparable and showed that these IL's are effective nitrosonium sources for the preparation of oximinoketones. The protocol is rapid, the yields are excellent, and the method is simple. Copyright
- Valizadeh,Shomali,Gholipour
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experimental part
p. 163 - 166
(2012/03/10)
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- Total synthesis of tryprostatins A and B
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Three distinct synthetic routes to the 2-prenyl tryptophan core skeleton of tryprostatins and their total syntheses are described. The strategies include a traditional gramine-mediated coupling reaction, Fuerstner indole synthesis, and our radical-mediated indole synthesis from o-alkenylphenyl isocyanide. The establishment of reliable conditions for the radical-mediated construction of indoles via a low-temperature radical initiator V-70 (2,2′-azobis(4- methoxy-2,4-dimethylvaleronitrile)) led to the highly efficient syntheses of tryprostatins A and B.
- Yamakawa, Takayuki,Ideue, Eiji,Iwaki, Yuzo,Sato, Ayumu,Tokuyama, Hidetoshi,Shimokawa, Jun,Fukuyama, Tohru
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scheme or table
p. 6547 - 6560
(2011/09/20)
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- New reactivity of oxaziridine: Pd(II)-catalyzed aromatic C-H ethoxycarbonylation via C-C bond cleavage
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A novel Pd(II)-catalyzed aromatic C-H ethoxycarbonylation with oxaziridine involving C-C bond cleavage is described. Various aromatic 2-phenylpyridines and related compounds as well as aryl ureas can be effectively ethoxycarbonylated. A catalytic cycle in
- Peng, Xingao,Zhu, Yingguang,Ramirez, Thomas A.,Zhao, Baoguo,Shi, Yian
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supporting information; experimental part
p. 5244 - 5247
(2011/12/04)
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- Total synthesis of the duocarmycins
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The total synthesis of (+)-duocarmycin A and SA through a common indoline intermediate is described. The key reactions include selective lithiation of a 2,6-dibromoiodobenzene derivative and diastereoselective addition to a chiral nitroalkene, copper-mediated aryl amination, and addition of aryllithium to azlactones. Copyright
- Yamada, Ken,Kurokawa, Toshiki,Tokuyama, Hidetoshi,Fukuyama, Tohru
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p. 6630 - 6631
(2007/10/03)
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- Indium metal as a reducing agent in organic synthesis
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The low first ionisation potential (5.8 eV) of indium coupled with its stability towards air and water, suggest that this metallic element should be a useful reducing agent for organic substrates. The use of indium metal for the reduction of C=N bonds in imines, the heterocyclic ring in benzo-fused nitrogen heterocycles, of oximes, nitro compounds and conjugated alkenes and the removal of 4-nitrobenzyl protecting groups is described. Thus the heterocyclic ring in quinolines, isoquinolines and quinoxalines is selectively reduced using indium metal in aqueous ethanolic ammonium chloride. Treatment of a range of aromatic nitro compounds under similar conditions results in selective reduction of the nitro groups; ester, nitrile, amide and halide substituents are unaffected. Likewise indium in aqueous ethanolic ammonium chloride is an effective method for the deprotection of 4-nitrobenzyl ethers and esters. Indium is also an effective reducing agent under non-aqueous conditions and α-oximino carbonyl compounds can be selectively reduced to the corresponding N-protected amine with indium powder, acetic acid in THF in the presence of acetic anhydride or di-tert-butyl dicarbonate. Conjugated alkenes are also reduced by indium in THF-acetic acid.
- Pitts,Harrison,Moody
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p. 955 - 977
(2007/10/03)
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- Synthesis of nucleosides and related compounds. XXXIV. Synthesis of 5- Isonitroso-1,3-dioxane-4,6-diones and their reactions
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Synthesis of 5-isonitroso-1,3-dioxane-4,6-dione (2: isonitroso Meldrum's acid) and related compounds and their reactions were described. Compound (2) reacted with various alcohols to give hydroxyiminoacetic acid esters in moderate yields. Compound 2 was a
- Katagiri,Nochi,Kurimoto,Sato,Kaneko
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p. 1251 - 1257
(2007/10/02)
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- SYNTHESE DE 1,2,3-TRIAZOLINES PAR CYCLOADDITION DIPOLAIRE-1,3 DE DIAZOALCANES A DES ESTERS D'OXIMES
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Oximino-cyanacetic or malonesters 1, 2, 3 and 4 lead with diazoalcanes RCHN2 (R = H, CH3, Ph) to 1,2,3-triazolines.These triazolines present a low stability, however they are obtained crystallized with good yields.They are fully characterized and orientation of the cycloaddition is established.
- Perrocheau, J.,Carrie, R.
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p. 749 - 760
(2007/10/02)
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- Porphyrins with Exocyclic Rings. 2. Synthesis of Geochemically Significant Tetrahydrobenzoporphyrins from 4,5,6,7-Tetrahydro-2H-isoindoles
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Benzo- and tetrahydrobenzoporphyrins are widespread constituents of oil shales and petroleum.Although the origins of these materials are not known, a case is made for divinylchlorophyll a, a widespread pigment in marine algae, being the precursor to many of these geoporphyrins.Total syntheses of four tetrahydrobenzoporphyrins related to etioporphyrin III are described.Tetrahydroisoindoles were prepared by condensation of isocyanoacetates with 1-nitrocyclohexene in the presence of DBU or by reaction of aminomalonates with 2-formylcyclohexanone.Condensation of 3-unsubstituted 4,5,6,7-tetrahydro-2H-isoindoles 23c and 23d with (acetoxymethyl)pyrroles in the presence of Montmorillonite clay gave dipyrrylmethanes 28a and 36a in excellent yield.Hydrogenolysis of the benzyl esters and subsequent acid-catalyzed condensation with pyrrole aldehydes 37a and /or 37b gave a series of a,c-biladiene dihydrobromides.Copper(II) mediated cyclization of the a,c-biladienes 32, 33, 35, and 38, followed by demetallation with 15percent sulfuric acid-trifluoroacetic acid, gave four isomeric tetrahydrobenzoporphyrins 10-13 in unusually high yield.This work provides a general route for the synthesis of these important porphyrin molecular fossils.
- May, Donald A.,Lash, Timothy D.
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p. 4820 - 4828
(2007/10/02)
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