Mass spectra of new heterocycles: VII. Main fragmentation channels of 2-(methylsulfanyl)-4,5-dihydro-3H-azepines under electronic ionization

Russian Journal of Organic Chemistry - Mass spectra of 3,7-di- and 3,6,7-trisubstituted 2-(methylsulfanyl)-4,5-dihydro-3H-azepines were investigated for the first time. The fragmentation of...     

Chalcogenation of 1,4-dichlorobut-2-yne with organic dichalcogenides in the system hydrazine hydrate–KOH

A reaction of organic dichalcogenides R₂Y₂ (R = Ph, Bn, Pr; Y = S, Se) with 1,4-dichlorobut-2-yne in the system hydrazine hydrate–KOH leads to four principal products: 1,4-bis(organylchalcogenyl)but-2-ynes, 1-organylchalcogenylbut-1-en-3-ynes, 4-organylchalcogenylbut-1-en-3-ynes, and 3(5)-methylpyrazole. The selectivity of the formation of individual products is determined by the ratio of the substrates used and the reaction temperature. A plausible mechanism of chalcogenation considered in the work agrees with the effect of the nature of chalcogene atoms and organic substituents R on stability of intermediates and products. The stabilization of carbanions by α chalcogene-containing groups corresponds to the following order: PhS > PhSe > BnS > BnSe > PrS.     

Efficient Synthesis of 1-(2-Propynyl)pyrrole

Russian Journal of Organic Chemistry -     

Mass Spectra of New Heterocycles: XX. Electron Impact and Chemical Ionization Mass Spectra of 5-(Prop-2-yn-1-ylsulfanyl)-1H-pyrrol-2-amines

Russian Journal of Organic Chemistry - Electron impact (70 eV) and chemical ionization (methane as reactant gas) mass spectra of 1-alkyl- and...     

Mass Spectra of New Heterocycles. XVII. Main Fragmentation Routes of Molecular Ions of 4-Alkoxy-5-amino-3-methylthiophene-2-carbonitriles under Electron and Chemical Ionization

For the first time decomposition was investigated of 4-alkoxy-5-amino-3-methylthiophene-2-carbonitriles under the conditions of electronic (70 eV) and chemical (reagent gas methane) ionization. At the electronic ionization the compounds under study [except for 4-(1-ethoxyethoxy) and 4-(ferrocenylmethoxy) derivatives] form stable molecular ions that decompose mainly by the cleavage of an alkyl radical from the alkoxy-substituent. Further fragmentation of the arising ion [M–Alk]⁺ depends on the substituent nature in the amino group. In the mass spectrum of 4-(ferrocenylmethoxy)-substituted thiophene peaks of the ion [FcCH₂]⁺ and its fragmentation products prevail. In the mass spectra of chemical ionization predominant peaks belong to ions M^+·, [M + H]⁺ and [M + C₂H₅]⁺, and fragment ions are absent.     

Unusual reaction of chloroacetyl chloride with 1,2-dichloroethene. Synthesis and properties of 2-chlorovinyl dichloromethyl ketone

The reaction of chloroacetyl chloride with 1,2-dichloroethene in the presence of AlCl₃ unexpectedly led to the formation of (E)-1,1,4-trichlorobut-3-en-2-one whose structure was proved by ¹H and ¹³C NMR, IR, and mass spectra and independent synthesis. A probable reaction scheme was proposed, which involves transformation of initially formed 1,2,4-trichloro-3-oxobutan-2-yl cation by the action of AlCl₃. The high reactivity of the vinylic halogen atom in (E)-1,1,4-trichlorobut-3-en-2-one was demonstrated by its reactions with nitrogen-centered nucleophiles (triethylamine, aniline, 3,5-dimethyl-1H-pyrazole) and sodium sulfide. These reactions involved only the C-Cl bond in the vinyl fragment and afforded (4,4-dichloro-3-oxobut-2-en-1-yl)triethylammonium chloride, 1,1-dichloro-4-phenylaminobut-3-en-2-one, 1-(4,4-dichloro-3-oxobut-2-en-1-yl)-3,5-dimethyl-1H-pyrazole, and 4,4′-thiobis(1,1-dichlorobut-3-en-2-one), respectively. The reaction of 1,1,4-trichlorobut-3-en-2-one with benzylhydrazine gave a mixture of 1,3- and 1,5-disubstituted pyrazoles.     

Mass spectra of linear and branched methyl(vinyl)siloxanes

The mass spectra of some linear and branched methyl(vinyl)siloxanes Me₃SiOSi(Me)(R)(OSiMeVin) _n Y (R=Vin, OSiMe₃; Y=OSiMe₃, Cl;n=0–2) were studied. The regularities of their fragmentation and an anomalously high probability of elimination of the ethylene molecule to form the stable 1,3-dioxa-2,4,6-trisilacyclohexane skeleton were revealed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 113–115, January, 1999.     

Reactions of 2,3-dichloro-1-propene with sulfur and tellurium in the system hydrazine hydrate-KOH

2,3-Dichloro-1-propene reacts with sulfur dissolved in the system hydrazine hydrate-KOH (with formation of K₂S₂ or K₂S) to afford bis(2-chloro-1-propene-3-yl)sulfide as the main product in both cases. Under similar conditions tellurium induces β-elimination of both chlorine atoms resulting in the formation of allene and complete regeneration of tellurium metal.     

New catalyst for the synthesis of 2-Phenyl-1,2,3-triazole

A new catalyst was developed for the synthesis of 2-phenyl-1,2,3-triazole: copper triflate Cu(OSO₂CF₃)₂. The process of cyclization of glyoxal phenylosazone in the presence of Cu(OSO₂CF₃)₂ was optimized that made it possible to increase the yield of the target product to 82%.