Selective synthesis of isomeric dithioglycerols

Reactions of 2,3-dibromopropan-1-ol and 1,3-dichloropropan-2-ol with elemental sulfur activated in the system hydrazine hydrate-2-aminoethanol at 30–35°C gave oligomeric polysulfides which were subjected to reductive cleavage with formation of individual dithioglycerol isomers. Activation of sulfur with the use of alkali gives rise to mixtures of isomeric products.     

Reactions of β,β′-dichlorodiethyl ether with elemental chalcogens and dimethyl dichalcogenides in the system hydrazine hydrate-base

β,β′-Dichlorodiethyl ether reacted with elemental selenium or tellurium, as well as with binary chalcogen mixtures (S/Se, S/Te, or Se/Te), activated in the system hydrazine hydrate-base to give oligomeric products containing oxygen and polychalcogenide fragments in the chain. Reductive cleavage of these oligomers gave rise to 3-oxapentane-1,5-dichalcogenols and their methyl derivatives. The latter were also synthesized from β,β′-dichlorodiethyl ether and the corresponding dimethyl dichalcogenides in the system hydrazine hydrate-KOH.     

Mass Spectra of New Heterocycles: XVIII. Electron Impact and Chemical Ionization Mass Spectra of Alkyl 5-Amino-3-methyl-4-(1H-pyrrol-1-yl)thiophene-2-carboxylates

Russian Journal of Organic Chemistry - Electron impact (70 eV) and chemical ionization (methane as reactant gas) mass spectra of alkyl 5-amino-3-methyl-4-(1H-pyrrol-1-yl)thiophene-2-carboxylates...     

Mass Spectra of New Heterocycles: XXIII. Electron Impact and Chemical Ionization Study of 5-[(Cyanomethyl)sulfanyl]- and 5-[(1,3-Dioxolan-2-ylmethyl)sulfanyl]-1H-pyrrol-2-amines

Russian Journal of Organic Chemistry - The fragmentation of 5-[(cyanomethyl)sulfanyl]- and 5-[(1,3-dioxolan-2-ylmethyl)sulfanyl]-1H-pyrrol-2-amines under electron impact (70 eV) and chemical...     

Effect of the chalcogen nature on the reaction of propane-1,3-dichalcogenolates with 2,3-dichloroprop-1-ene

The direction of the reaction of propane-1,3-dichalcogenolates with 2,3-dichloroprop-1-ene in the system hydrazine hydrate-KOH depends not only on the conditions but to a greater extent on the chalcogen nature. Dipotassium propane-1,3-dithiolate and propane-1,3-diselenolate give rise to products of substitution of the chlorine atom on the sp ³-carbon atom, which are capable of undergoing further transformations (domino reaction). Dipotassium propane-1,3-ditellurolate promotes elimination of both chlorine atoms with formation of allene.     

Selenoacetalyzation of 4‐Formylpyrazoles in the Presence of Trimethylchlorosilane

The reaction of 3,5‐dimethyl‐4‐formylpyrazoles, bearing various substituents at N‐1 atom, with propane‐1,3‐diselenol and 2‐hydroxypropane‐1,3‐diselenol in the presence of ТМSCl proceeds without heating to chemoselectively give hitherto unknown 2‐(pyrazol‐4‐yl)‐1,3‐diselenane hydrochlorides in high yields. The latter are easily transformed to the corresponding free bases—2‐(pyrazol‐4‐yl)‐1,3‐diselenanes. The ¹⁵N chemical shifts of the pyrazole ring in 2‐(pyrazol‐4‐yl)‐1,3‐diselenanes obtained by 2D HMBC‐gp (¹⁵N‐¹H) technique are indicative of the N‐2 atom protonation in hydrochlorides.     

Synthesis of the thiophene series 1,3-diselenanes

Direct reaction of propan-1,3-diselenol with thiophene-2-carbaldehydes in trimethylchlorosilane medium is studied. Synthetic procedure for preparation of the previously unknown 1,3-diselenanes of thiophene series is developed. Structure of the newly obtained compounds is established by ¹H, ¹³C, and ⁷⁷Se NMR spectroscopy. Chromatomass spectrometric stidy of the products obtained is carried out. In some cases reaction may be directed to the synthetis of new types of polymers of original structure.     

Reactions of chloromethyloxirane and dihalopropanols with chalcogens in basic reducing systems

Chloromethyloxirane and 2,3-dibromopropan-1-ol reacted with a solution of selenium or tellurium in the system hydrazin hydrate-potassium hydroxide (K₂Se₂, K₂Te₂) to give allyl alcohol; the reaction was accompanied by regeneration of the initial free chalcogen. 1,3-Dichloropropan-2-ol reacted with selenium in the same system to give oligomeric product having a 2-hydroxypropane-1,3-diyldiseleno monomeric unit, while the reaction with tellurium led to the formation of allyl alcohol and almost complete regeneration of initial tellurium. Probable reaction mechanisms are discussed. Polyselenide oligomers containing a hydroxy group in a monomeric unit were formed in reactions of chloromethyloxirane and 1,3-dichloropropan-2-ol with selenium in the system hydrazine hydrate-2-aminoethanol. Under analogous conditions 2,3-dibromopropan-1-ol was converted into allyl alcohol with regeneration of elemental selenium. Reductive cleavage of polyselenide oligomers gave Se-methyl derivatives of 2-hydroxypropane-1,3-diselenol.     

1-Alkylpyrazoles and 1-alkyl-5-chloropyrazoles from halovinyl ketones and 1,1-dialkylhydrazines

Regioselective heterocyclization of alkyl 2-chloro-and 2,2-dichlorovinyl ketones with 1,1-dialkyl-hydrazines to 1,3-dialkyl-1H-pyrazoles and 1,3-dialkyl-5-chloro-1H-pyrazoles involves intermediate formation of the corresponding dialkylhydrazones. Fragmentation pattern of chlorine-containing pyrazoles, 3-chloromethyl-1-methyl-1H-pyrazole and 5-chloro-1-methyl-3-propyl-1H-pyrazole, depends on the position of the halogen atom.     

Reaction of divinyl telluride with secondary phosphine chalcogenides

Divinyl telluride reacted with 2 equiv of diphenylphosphine sulfide in the presence of AIBN as radical initiator (63–68°C) to give the corresponding anti-Markovnikov adduct in 68% yield with high regioselectivity. Treatment of the addition product with aqueous hydrogen peroxide at room temperature afforded 71% of vinyldiphenylphosphine oxide. Radical addition of diphenylphosphine selenide to divinyl telluride (AIBN, 63–68°C) led to the formation of 1,1,3,3-tetraphenyldiphosphoxane 1,3-diselenide in 82% yield.