2,5-dihalothiophenes in the reaction with chlorosulfonic acid

The mixtures of mono-and dihalothiophenesulfonyl chlorides, formed in the sulfochlorination reaction of 2,5-dichlorothiophene and 2,5-dibromothiophene, were treated with aqueous ammonia and thus converted into mixtures of the corresponding stable thiophenesulfonamides. The structure and composition of the latter were studied by physicochemical methods: GC-MS and ¹H, ¹³C, ¹H-¹³C HSQC, ¹H-¹³C HMBC, and NOESY NMR spectroscopy. As a result of the above chemical transformations, 2,5-dichlorothiophene afforded a mixture of 5-chlorothiophene-2-sulfonamide and 4,5-dichlorothiophene-3-sulfonamide in a roughly 70:30 ratio. In the case of 2,5-dibromothiophene, a mixture of 5-bromothiophene-2-sulfonamide, 4,5-dibromothiophene-3-sulfonamide, and 3,5-dibromothiophene-2-sulfonamide (3:54:43) was formed. Original Russian Text I.B. Rozentsveig, Yu.A. Aizina, K.A. Chernyshev, L.V. Klyba, E.R. Zhanchipova, E.N. Sukhomazova, L.B. Krivdin, G.G. Levkovskaya, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 5, pp. 831–836.     

Synthesis and characteristics of the mass spectra of 2,5-dimercapto-2,5-dimethyltetrahydrothiophene

2,5-Dimercapto-2,5-dimethyltetrahyrothiophene was synthesized by the reaction of 1-iodopropan-2-one with hydrogen sulfide in an ether solution of hydrogen chloride at-70°C. Its structure was established by mass spectrometry, ¹H and ¹³C NMR spectroscopy. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 216–219, February, 2007.     

Mass Spectra of New Functionally Substituted Heterocycles: V. First Example of McLafferty Rearrangement in the Series of 5-(1-Ethoxyethoxy)-2,3-dihydropyridines and 3-(1-Ethoxyethoxy)pyridines Derived from α-Lithiated 1-(1-Ethoxyethoxy)allene and Methoxymethyl Isothiocyanate

Previously unknown 5-(1-ethoxyethoxy)-2-methoxy-6-methylsulfanyl-2,3-dihydropyridine, 3-(1-ethoxyethoxy)-2-methylsulfanylpyridine, and 2-methylsulfanylpyridin-3-ol were synthesized from α-lithiated 1-(1-ethoxyethoxy)allene, methoxymethyl isothiocyanate, and methyl iodide, and their fragmentation under electron impact was studied. At ionizing electron energies of 12 and 60 eV in the temperature range from 50 to 250°C, the molecular ions derived from 5-(1-ethoxyethoxy)-2-methoxy-6-methylsulfanyl-2,3-dihydropyridine and 3-(1-ethoxyethoxy)-2-methylsulfanylpyridine decompose along two main pathways: rupture of the C-O bond in the acetal moiety to give oxonium ions with m/z 73 (in the two cases) and 168 (pyridine derivative) and unexpectedly facile McLafferty rearrangement with elimination of ethoxyethene molecule to produce fragment ions with m/z 173 and 141, respectively. The latter pathway was not observed previously for dihydropyridines and acetals, and it predominates in the fragmentation of 3-(1-ethoxyethoxy)-2-methylsulfanylpyridine. Expulsion of methanol molecule from the molecular ion of 5-(1-ethoxyethoxy)-2-methoxy-6- methylsulfanyl-2,3-dihydropyridine occurred only above 170°C.     

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...     

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.     

Synthesis and oxidative cleavage of poly(trimethylene diselenides)

1-Bromo-3-chloropropane and elemental selenium react in hydrazine hydrate-alkali and hydrazine hydrate-amine systems to form poly(trimethylene diselenides). The reductive cleavage of the resulting selenokols yielded 1,3-propanediselenol, 1,2-diselenolane, and bis(alkylseleno)propanes. These compounds are important reagents for organic synthesis and ligands for complex formation. The products obtained were studided by GC-MS.     

Reaction of 1-bromo-3-chloropropane with tellur and dimethyltelluride in the system of hydrazine hydrate-alkali

A synthesis of oligomeric substance of thiocol type, the poly(trimethyleneditelluride), from 1-bromo-3-chloropropane and elemental tellurium is performed using a hydrazine hydrate-alkali system. Reductive splitting of the tellurocol followed by alkylation with methyl iodide give rise to preparation of bis(methyltelluro)propane, which was synthesized also from dimethyltelluride and 1,3-dihalopropanes using the N₂H₄·H₂O/KOH system. Mass spectra of the synthesized low molecular weight organotellurium compounds are considered.     

Reactions of dichloromethane with chalcogens and dimethyl chalcogenides in the hydrazine hydrate-alkali system

Methods of synthesis of compounds MeY(CH₂Y) _n Me (Y=S, Se, Te; n = 1–3) containing several identical or different chalcogen atoms are suggested. The methods are based on the reactions of dichloromethane with elemental chalcogens (Y^2?) and dimethyl dichalcogenides (MeY^?) activated in the system hydrazine hydrate-alkali. The effect of the chalcogen on the reactivity toward dichloromethane is qualitatively assessed. With elemental tellurium in the system hydrazine hydrate-alkali, reduction of one chlorine atom in dichloromethane and formation of methyltellanyl derivatives are observed.     

Distinguishing Features of reactions of 2-chloro-and 2,2-dichloro(bromo)vinyl ketones with alkyl-and arylhydrazines

2-Chlorovinyl alkyl ketones react with alkylhydrazines to give mixtures of 1-R-3-R′- and 1-R-5-R′-pyrazoles: The 1-R-3-R′-pyrazoles form through the heterocyclization of 2-chlorovinyl ketone alkylhydrazones whereas in the heterocyclization into 1-R-5-R′-pyrazoles N ¹-alkyl-N ²-(2-acylvinyl)hydrazines are involved. The regiospecific heterocyclization of 2-chloro-and 2,2-dichlorovinyl ketones with arylhydrazines and also of 2,2-dichloro(bromo)vinyl trifluoromethyl ketones with C alkylhydrazines into pyrazoles and 5-chloro(bromo)-pyrazoles proceeds through a stage of haloenones hydrazones formation. The study of the structure of the obtained 1-alkyl-3(5)-alkylpyrazoles by means of two-dimenaional ¹H and ¹³C NMR spectroscopy and GC-MS method made it possible to assign the proton and carbon signals of isomeric pyrazoles and to establish the diagnostic ions for the pair of 1,3-and 1,5-isomers.     

Mass spectra of new functionally substituted heterocycles: VI. Fragmentation of 3-methoxy-7-methyl-2-methylsulfanyl-4,5-dihydro-3H-azepine, its structural isomers, 5-methoxy-2,2-dimethyl-6-methylsulfanyl-2,3-dihydropyridine and 1-isopropyl-3-methoxy-2-methylsulfanyl-1H-pyrrole, and their linear precursors under electron impact

Mass spectra of previously unknown isomeric 1-isopropyl-3-methoxy-2-methylsulfanylpyrrole, 5-methoxy-2,2-dimethyl-6-methylsulfanyl-2,3-dihydropyridine, and 3-methoxy-7-methyl-2-methylsulfanyl-4,5-dihydro-3H-azepine were studied for the first time. Fragmentation of all heterocyclic compounds under electron impact begins with elimination of methyl radical, and the subsequent decomposition of the [M ? Me]⁺ ion (m/z 170) is specific for each isomers, which ensures their reliable identification in reaction mixtures. The corresponding linear precursors, methyl N-isopropyl-2-methoxybuta-2,3-dienimidothioate and 2-methoxy-N-(1-methylethylidene)-1-methylsulfanylbuta-1,3-dien-1-amine undergo isomerization and decomposition even under very mild temperature conditions, so that their mass spectra could not be recorded.