Mass-spectrometric study of the cyclization of diazo compounds. 10. 2-Diazomalonic acid amides. Mass spectra of the negative ions

The mass spectra of the negative ions of the dissociative resonance capture of electrons of diazo amides and the isomeric triazoles were studied. The molecular negative ions of these compounds are unstable and do not undergo interisomerization. The principal fragmentation process involves the elimination of a molecule of nitrogen and transformation of the resulting [M-N₂]^– ions to the heterocyclic form, which is the same for the two isomers.See [1] for communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 941–944, July, 1987.     

Mass-spectrometric study of the cyclization of diazo ketones. 4. Cyclization of N'-phenyl-3-ureido- and N'-phenyl-3-thioureido-1-diazoalkan-2-ones. 2-Anilino-5,6-dihydro-4H-1,3-thiazin-5-ones

A comparison of the mass spectra of N'-phenyl-3-thioureido-1-diazo-alkan-2-ones (I) with the mass spectra of 2-anilino-5,6-dihydro-4H-1,3-thiazin-5-ones (II) and N'-phenyl-3-ureido-1-diazoalkan-2-ones (III) makes it possible to conclude that under the influence of electron impact the molecular ions of the diazo ketones, through the loss of a molecule of nitrogen, undergo only partial cyclization to the corresponding thiazinones (oxazinones in the case of III). In the case of diazo ketones III virtually all of the [M-N₂]⁺ ions undergo fragmentation without cyclization. Under chemical-ionization conditions (with isobutane as the gas-reactant) the principal fragmentation of the protonated ions of I and III entails cleavage of the C-N bonds. Only a small part of these ions lose a molecule of nitrogen, but it is impossible to establish the structures of the resulting [MH-N₂]⁺ ions from the mass-spectrometric data.See [1], for communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 473–480, April, 1983.     

Brønsted Acid Catalyzed Friedel–Crafts‐Type Coupling and Dedinitrogenation Reactions of Vinyldiazo Compounds

The direct Friedel–Crafts‐type coupling and dedinitrogenation reactions of vinyldiazo compounds with aromatic compounds using a metal‐free strategy are described. This Brønsted acid catalyzed method is efficient for the formation of α‐diazo β‐carbocations (vinyldiazonium ions), vinyl carbocations, and allylic or homoallylic carbocation species via vinyldiazo compounds. By choosing suitable nucleophilic reagents to selectively capture these intermediates, both trisubstituted α,β‐unsaturated esters, β‐indole‐substituted diazo esters, and dienes are obtained with good to high yields and selectivity. Experimental insights implicate a reaction mechanism involving the selective protonation of vinyldiazo compounds and the subsequent release of dinitrogen to form vinyl cations that undergo intramolecular 1,3‐ and 1,4‐ hydride transfer processes as well as fragmentation.     

酸促进2-乙烯基苯胺与重氮的[5+1]环化合成2-芳基喹啉

利用廉价易得的2-乙烯基苯胺与重氮化合物在三氟乙酸催化下发生[5+1]环化反应, 以中等至良好的产率合成了24种2-芳基喹啉衍生物. 该方法无需金属催化剂, 官能团兼容性好, 反应成本低, 不仅拓展了重氮化合物参与的新型有机反应, 同时也为2-芳基取代喹啉的合成提供了高效、 经济且简洁的新方法.     

2-Diazomethyl-4-furanones. Synthesis and properties

1,5-Bisdiazo-3-alkylpentane-2,4-diones were synthesized by the reaction of alkylmalonic acid chlorides with diazomethane; the products readily undergo intramolecular cyclization at the oxygen atom and one of the diazoacetyl groups under the influence of acidic agents with the formation of 2-diazomethyl-3-alkyl-4-furanones. It is shown that diazomethyl-4-furanones, which are vinylogs of -diazo ketones, undergo reactions that are characteristic for aliphatic diazo compounds. The structure of the product of 1,3-dipolar cycloaddition of dimethyl acetylenedicarboxylate to a diazomethyl-4-furanone was investigated by means of x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 454–459, April, 1988.     

9-Diazo-10,10-dimethyl-9,10-dihydro-10-sila-2-azaanthracene and 10,10-dimethyl-4′-oxospiro[9,10-dihydro-10-sila-2-azaanthracene-9,2′-azetidine]

The synthesis of the first representative of diazo compounds in the dihydrosilaazaanthracene series and a spiro compound with dihydrosilaazaanthracene and azetidine fragments was realized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 272–275, February, 1990.     

1,2-Thio group migration in Rh(II) carbene reactions

[reaction: see text] A series of beta-thio group substituted alpha-diazo carbonyl compounds have been prepared by nucleophilic substitution reactions of thiophenol, thionaphthol, or benzyl mercaptan with beta-acetoxy-alpha-diazo carbonyl compounds. The diazo decomposition of these diazo carbonyl compounds with various transition metal catalysts, including Rh(II) carboxylates and Cu(I) and Cu(II) complexes, has been investigated. It was found that the diazo decomposition of these compounds gave 1,2-thio group migration products. No 1,2-hydride or 1,2-aryl migration products were observed in all cases.     

Mass spectra of 3-arylidene-1H-2,3-dihydro-1,4-benzodiazepin-2-ones

The scheme of the fragmentation of arylidene derivatives of 5-phenyl-1,4-benzodiazepin-2-ones was established by means of high-resolution mass spectrometry. One of the principal fragmentation pathways of these compounds is cleavage of the 2C-3C and 4N-5C bonds to give two fragments. Depending on the substituents in the arylidene portion of the molecule, the charge is localized primarily on one or the other of these fragments. The mechanism of the formation of the [ArCH₂]⁺ ions observed in the mass spectra of all of the investigated compounds was established on the basis of the mass spectrum of the 1N-deuterium-labeled compound. The specific fragmentation pathways due to the ortho effect of the nitro group are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1690–1696, December, 1976.     

Chemistry of Phosphorus Ylides. Part 40. Synthesis of Pyrazoles by the [3 + 2] Cycloaddition of Diazo Compounds with Wittig Reagents as Antimicrobial Compounds

A comparative study between the reactions of active phosphacumulenes and stabilized phosphonium ylides on some diazo compounds have been performed. A number of substituted phosphanylidene spiro pyrazoles have been synthesized from the reaction of the active phosphacumulenes and the diazo derivatives. On the other hand, treatment of the diazo substrates with the stabilized phosphonium ylides led to the formation of the corresponding ylidenes and diazenyl phosphanylidenes. The antimicrobial activities for the new compounds are also reported.     

Photoredox-Enabled Self-(3+2) Cyclization of Vinyldiazo Reagents: Synthesis of Cyclopentenyl α-Diazo Compounds

A photocatalytic self-(3+2) cycloaddition of vinyldiazo compounds is described, which provides cyclopentene derivatives with conservation of one diazo functional group. Experimental insights and density functional theory indicate that the reaction is triggered by an unusual single electron oxidation of vinyldiazo compounds, while the photolysis for the generation of free carbene species is not involved. The synthetic applications of the resulting cyclopentenyl α-diazo compounds were demonstrated based on the rich chemistry of the diazo functional group.     

Olefination of 3-diazopiperidin-2-one

New conditions have been developed for the olefination of diazo compounds catalysed by methyl trioxorhenium. The new system is suitable for unreactive diazo compounds and its utility is demonstrated by the olefination of 3-diazopiperidin-2-one with a range of aromatic, heterocyclic and alkylaldehydes.     

New Syntheses of Diazo Compounds

Diazo compounds (R¹R²C?N₂) are known as versatile and useful substrates for an array of chemical transformations and, therefore, diazo chemistry is still far from losing anything of its long‐standing fascination. In addition to many studies on the subsequent chemistry of the diazo group, the inventory of methods for the preparation of diazo compounds is continuously supplemented by new methods and novel variations of established procedures. Several of these synthetic approaches take into account the lability and remarkable chemical reactivity of certain classes of diazo compounds, and environmentally more benign procedures also continue to be developed.     

Heterocyclization of compounds containing diazo and cyano groups. 2. Synthesis and recyclization of 4-substituted 5-amino-1,2,3-thiadiazoles

The reaction of carbonyl derivatives of diazoacetonitrile with hydrogen sulfide in the presence of triethylamine yields 4-substituted 5-amino-1,2,3-triadiazoles. Under analogous conditions, hydrogen selenide and ethyl mercaptan reduce the starting diazo compounds to hydrazones. Thiadiazoles are recyclized to 4-substituted 5-mercapto-1,2,3-triazoles by the action of bases.For 1, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 691–696, May, 1986.     

Azines and azoles. 64. Mass spectra and tautomerism of 2-aryl-4,6-dioxo-1,3-thiazines

Mass spectra of 2-aryl-4,6-dioxo-1,3-thiazines were studied and the general fragmentation paths of these compounds determined. Based on mass spectra of compounds with fixed structures, 2-aryl-5,5-dialkyl-4,6-dioxo-1,3-thiazines, 4-alkoxy- and 4-acyloxy-2-aryl-6-oxo-1,3-thiazines, the decomposition paths of the dicarbonyl and hydroxycarbonyl forms were determined. It was concluded on the basis of the obtained data that 2-aryl-4,6-dioxo-1,3-thiazines exist in the gas phase predominantly in the hydroxycarbonyl form.For Communication 63, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1409–1412, October, 1987.     

Oxorhenium complexes as aldehyde-olefination catalysts

Several oxorhenium compounds in the formal oxidation states V and VII are examined as catalysts for the aldehyde-olefination starting from diazo compounds, phosphines, and aldehydes. Of these, [ReMeO2(eta2-alkyne)] complexes provide the simplest catalysts to study, although [ReOCl3(PPh3)2] still remains the most efficient rhenium catalyst for aldehyde-olefination described to date. Prior to the reaction with the Re catalysts the phosphine and the diazo compound react to form a phosphazine. No catalytic reaction occurs in cases where no phosphazine formation is observed. The first step of the catalytic cycle involves the formation of a carbene intermediate by the reaction of phosphazine and catalyst under extrusion of phosphine oxide and dinitrogen. In a second step the carbene reacts with aldehyde under olefin formation and catalyst regeneration. Excess of alkyne as well as the presence of ketones slows down the catalytic reaction. The olefination of 4-nitrobenzaldehyde with diazomalonate is possible with these Re catalysts. In contrast, this reaction does not take place either in the classical Wittig fashion from Ph3P=C(CO2Et)2 and aldehyde or by use of all other catalysts for aldehyde olefination reactions reported to date. Catalytic ylide formation from diazo compounds seems therefore not to be the only pathway through which catalytic aldehyde-olefination reactions can proceed.     

Mass spectrometry and structures of ions of heterocyclic compounds activated by collision. 2. 2-Methylnitroindolizines

The principal pathways of the fragmentation of 2-methylnitroindolizines were investigated. The fragmentation and structures of the isomeric [M-OH]⁺ and [M-NO]⁺ ions formed in the fragmentation of these compounds were studied by the method of dissociative activation by collision (DAC). It was established that the stable [M-OH]⁺ ions formed in the fragmentation of the 1- and 3-nitro isomers as a result of the ortho effect have different structures and that their DAC spectra can be used to determine the position of the nitro group in the molecule.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1631–1635, December, 1988.     

Synthesis and properties of azoles and their derivatives. 25. Electron-impact mass spectra of nitro- and nitroalkyl-substituted 3-aryl-δ2-isoxazolines

The fragmentation of nitro and nitroalkyl derivatives of 3-aryl-²-isoxazolines under the influence of electron impact was investigated. It was established that the fragmentation of the molecular ions of these compounds takes place primarily through the nitro- and halogen-containing groups; other pathways of dissociative ionization include the most important pathways of the fragmentation of arylisoxazoles.See [1] for Communication 24.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 980–983, July, 1990.     

Reactivity of diazoazoles and azolediazonium salts in <Emphasis Type="Italic">C</Emphasis>-azo coupling reactions

The comparative reactivity of heterocyclic diazo compounds and the corresponding diazonium salts in C-azo coupling reactions was studied using imidazole, pyrazole, and triazole derivatives as examples.The reactivities of pyrazole- and imidazole-derived diazonium salts are much lower than those of thiadiazole- and 1,2,4-triazole-derived diazonium salts but higher than those of pyrrole and indole diazo compounds.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 348–358, February, 2005.     

Synthesis and study of the properties of tetrazoles,azides, triazenes,and azo compounds of the thiadiazole series

Azo compounds and bistriazenes were obtained by diazo coupling of diazotized 5-amino-2-R-1,3,4-thiadiazoles; tetrazolo[4,5-b]-1,3,4-thiadiazoles, to which azido-tetrazole tautomerism is peculiar, were obtained by replacement of the diazo group by an azido group. The structures of the products were confirmed by their IR and UV spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 933–936, July, 1980.     

Mass-spectral behavior of 2-azatriptycene and its derivatives

The mass-spectral behavior of 11 aromatic and partially hydrogenated 2-azatriptycenes was investigated. It was established that the principal fragmentation pathway for these compounds is the formation of [M-nH] ⁺ and [M-nH]²⁺ ions (n = 1–6), as well as pseudoretrodiene fragmentation of the heterocyclic ring with the elimination of the atoms in the 2 and 3 positions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1399–1402, October, 1981.