Amination of anthra [ 1, 9-c,d ] isoxazol-6-ones

The behavior of 3,5-dihalo derivatives of anthra[1, 9-c,d]isoxazol-6-one with respect to primary and secondary amines was studied. 5-Chloroanthra[1,9-c,d]isoxazol-6-one undergoes amination particularly readily. The products of the reaction of isoxazoles with amines are the corresponding amino derivatives. The amination of 5-chloroanthra[1,9-c,d] isoxazol-6-one in refluxing dimethylformamide (DMF) is accompanied by reductive cleavage of the isoxazole ring and the formation of 1-amino-4-arylaminoanthraquinones. Amination in the 5 position with substitution of a hydride ion takes place primarily in the reaction of 3-chloroanthra[1,9-c,d]isoxazol-6-one with benzylamine of cyclohexylamine, whereas the chlorine in the 3 position is replaced by the action of morpholine or piperidine on the same substrate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 912–915, July, 1980.     

Oxazolo[4,5-d]isoxazole Derivatives and 3,4-Disubstituted Isoxazoles from Isoxazol-5(4H)-ones

Synthesis for oxazolo[4,5-d]isoxazole derivatives and 3,4-disubstituted isoxazoles from isoxazol-5(4H)-ones is reported.     

Transformations of anthra[1,9-cd]isoxazol-6-ones in hydrohalic acids

4-Halo-1-aminoanthraquinones are formed when anthra [1,9-cd]isoxazol-6-ones are refluxed in hydrohalic acids. The 3 position undergoes halogenation when 5-substituted isoxazoles are used. The process takes place via a one-proton mechanism with the participation of halide ion in the rate-determining step, possibly with the intermediate formation of N-haloaminoanthraquinones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1471–1473, November, 1980.     

Mass spectral fragmentation pattern of 3-methyl- and 3-phenyl-4-(N-methylarylhydrazono)isoxazol-5-ones

3-Methyl-4-(N-methylarylhydrazono)isoxazol-5-ones and 3-phenyl-4-(N-methylarylhydrazono)isoxazol-5-ones undergo considerable fragmentation on electron impact involving rupture of the isoxazolone ring and bonds in the N-methylarylhydrazono side chain.     

Etude de l'équilibre azido ⇌ tétrazole dans la séric du thiazolo[2,3-e]-tétrazole. III. Effects des substituants

The substituent effects on azido/tetrazole equilibrium on a series of 2-substituted thiazoles, benzothiazoles, thiadiazoles, benzoxazoles and isoxazoles has been studied by proton magnetic resonance in two solvents (DMSO-d₆ and deuteriochloroform). For thiazole an excellent Hammett relationship was found, both for the 4 and 5 positions.     

Ionisation et Fragmentation en Spectrométrie de Masse. VII—Structure de l'Ion [C6H6O]+ Issu de la Décomposition du Phényléthyléther Sous Impact Electronique

The activation energy is calculated for the fragmentation [C₆H₅OC₂H₅]⁺ → [C₆H₆O]⁺ +C₂H₄. Estimation of the enthalpy difference between the final state and the molecular ion supports the formation of a phenol-like structure for the [C₆H₆O]⁺ ion. The activation energy for backward reaction is compared with the mean kinetic energy release. Whether this is a concerted or non-concerted fragmentation is discussed.     

The mass spectra of potential antidiabetics: 4-Arylhydrazono-3-methyl isoxazol-5-ones and pyrazol-5-ones

The mass spectra of variously substituted 4-arylhydrazono-3-methyl isoxazol-5-ones and pyrazol-5-ones have been examined, and the fragmentation pathways elucidated. The spectra of the former compounds differ from previously reported 4-arylidene derivatives and this difference has been attributed to fragmentation involving the ? NH? N?moiety. The investigation has shown up some interesting ‘ortho effects’ as well as the facile loss of HN?C?NH from N-amidino derivatives of the pyrazol-5-ones.     

Electron impact mass spectrometry of 3-methyl-4-benzylideneamine-5-styrylisoxazoles. II

The mass spectra of a series of substituted 3-methyl-4-benzylideneamine-5-styrylisoxazoles are reported and discussed. The spectra of these isoxazoles show a characteristic fragmentation pattern different from the 5-styryl-4-nitroisoxazoles. Perhaps this is due to the presence of the Schiff base at position 4.     

Recent Progress on Cyclic Nitrenoid Precursors in Transition-Metal-Catalyzed Nitrene-Transfer Reactions

Nitrene-transfer reactions are powerful synthetic tools for the direct incorporation of nitrogen atoms into organic molecules. The discovery of novel nitrene-transfer reactions has been dominantly supported not only by improvements in transition-metal catalysts but also by the employment of novel precursors of nitrenoids. Since pioneering work involving the use of organic azides and iminoiodinanes as practical synthetic tools for nitrogen-containing compounds was reported, a new approach using various N-heterocycles containing strain energy or a weak bond has emerged. In this review, we briefly summarize the history of nitrene-transfer chemistry from the viewpoint of its precursors. In particular, the use of N-heterocycles such as 2H-azirines, 1,4,2-dioxazol-5-ones, 1,2,4-oxadiazol-5-ones, isoxazol-5(4H)-ones, and isoxazoles is comprehensively described, showing the recent remarkable progress in this chemistry.     

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.     

Utilisation du 13C en Spectrométrie de Masse: Etude de la Fragmentation de Disaccharides

Twenty-nine α,β-(1 → 3) and (1 → 4) or β-(1 → 6) disaccharides, in the glucose series were analysed by electron impact mass spectrometry. In addition to the known mechanism, a few ¹³C labelled compounds led us to suggest that the ion c was formed from the reducing unit B and the C-1′ of the non-reducing residue A, while A was the starting point for rearrangement and fragmentation processes.     

Ionisation et Fragmentation en Spectrométrie de Masse. VI—Energie d'Activation de la Fragmentation Principale des Monohalogénobenzènes

The activation energy of the fragmentation [C₆H₅X?]⁺ → [C₆H₅]⁺ + X? (X = Cl, Br, I) is calculated by various methods. These results are compared with determinations of kinetic energy release and with rate constant values available in the literature.     

Préparation d'isoxazoles trisubstitués par réduction chimique et électrochimique d'α-acyl β-nitrostilbènes

Nitration of α-acylstilbenes with dinitrogen tetroxide leads to corresponding Z-α-acyl-β-nitrostilbenes. By chemical or electochemical reduction of these compounds, trisubstituted isoxazoles were prepared in good yields.     

Total Synthesis of (±)-α-Acoradiene via Intramolecular Photoaddition and Reductive Cyclobutane Cleavage

(±)-α-Acoradiene (4) has been synthesized from 3-methoxy-2-cyclohexenone by a sequence of 8 steps. The key steps (Scheme 6) are the regio- and stereoselective photo[2+2]addition 7→6 and the reductive fragmentation 6→5 .     

Reaction of (<Emphasis Type="Italic">p</Emphasis>-alkoxyphenyl)-acetothioamides with acetylene-dicarboxylic esters

The condensation of p-methoxy(ethoxy)phenylacetothioamides with acetylenedicarboxylic esters leads to two condensation products, 2-(alkoxycarbonylmethylene)-4-(4-methoxy(ethoxy)phenyl)-5-morpho-lino-3H-thiophen-3-ones and 2-(alkoxycarbonylmethylene)-4-(4-methoxy(ethoxy)phenyl)-5-alkoxy-3H-thiophen-3-ones. It was shown that the substitution of the morpholino group is intramolecular. For the jubilee of O. N. Chupakhin Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 541–545, April, 2009.     

含异噁唑环的新型2,5-二取代-1,3,4-噁二唑的合成及其杀菌活性

以取代异噁唑甲酸乙酯为起始原料,经取代、加成与环化反应合成了5个新型2-取代苯胺基-5-(取代异噁唑-4-基)-1,3,4-噁二唑(5a～5e),产率54.0％～86.7％,其结构经1H NMR,IR和元素分析表征.初步杀菌活性试验表明,5a,5c和5d对番茄灰霉病菌有很高的抑制作用,其活性高于对照药剂多菌灵.     

Novel copolymers of styrene. 9. Fluoro ring-disubstituted butyl 2-cyano-3-phenyl-2-propenoates

Electrophilic trisubstituted ethylenes, ring-disubstituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH?C(CN)CO₂C₄H₉ (where R is 2-fluoro-5-methoxy, 2-fluoro-6-methoxy, 3-fluoro-4-methoxy, 4-fluoro-3-methoxy, 5-fluoro-2-methoxy, 3-fluoro-2-methyl, 3-fluoro-4-methyl, 4-fluoro-2-methyl, 4-fluoro-3-methyl, 5-fluoro-2-methyl were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and butyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copoly-merized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C-NMR. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (1.2–3.5% wt.), which then decomposed in the 500–800°C range.     

Unusual reaction between 6H-6-oxo-5-haloanthra[1,9-cd]-isoxazoles and quinoline

The reaction of 6H-6-oxo-5-haloanthra[1,9-cd]isoxazoles with quinolines leads to unexpected fragmentation of the quaternized quinoline ring to give xylidine or o-toluidine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1682–1686, December, 1986.     

Synthesis of trisubstituted isoxazoles by palladium(II)-catalyzed cascade cyclization-alkenylation of 2-alkyn-1-one O-methyl oximes

A palladium-catalyzed, cascade 5-endo-dig cyclization-alkenylation synthesis of isoxazoles has been developed. The addition of 1 equiv of n-Bu(4)NBr significantly increases the yield of the desired 4-alkenyl-3,4,5-trisubstituted isoxazoles. A variety of trisubstituted isoxazoles are prepared in moderate to excellent yields. One example of the synthesis of a naphthoisoxazole is reported by a cascade cyclization-alkenylation-Heck reaction.     

Interaction of 3-amino-2-(isoxazol-3-yl)-4-methoxymethyl-6-methyl-thieno[2,3-<Emphasis Type="Italic">b</Emphasis>]pyridine with Raney nickel

3-Amino-2-(isoxazol-3-yl)-4-methoxymethyl-6-methylthieno[2,3-b]pyridine was synthesized by the reaction of 2(1H)-thioxopyridine-3-carbonitrile with 3-chloromethylisoxazole in the presence of two equivalents of KOH. Boiling of 3-amino-2-(isoxazol-3-yl)-4-methoxymethyl-6-meth-ylthieno[2,3-b]pyridine with Raney nickel results in 4-aminothieno[2,3-b;4,5-b′]dipyridine or 5-(4-amino-2-pyridyl)pyridine depending on the reaction conditions. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 669–670, March, 2008.