G. I. Sarapulova

1,3-dipolar cycloaddition of trimethylsilyl azide to propynals and dimerization of 1H-1,2,3-triazole-5-carbaldehydes to tricyclic bis-hemiaminals

Reactions of trimethylsilyl azide with 3-trimethylsilyl-2-propynal and 2-propynal were studied. X-Ray analysis of the molecular structure of 4-trimethylsilyl-1H-1,2,3-triazole-5-carbaldehyde showed that the carbonyl group appears in the s-cis conformation with respect to the double C=C bond in the heteroring. The effect of the temperature and polarity of the medium on the ability of 1H-1,2,3-triazole-5-carbaldehyde to undergo dimerization to tricyclic bis-hemiaminals was examined by IR and 1H NMR spectroscopy.

Synthesis of 5-trimethylsilylethynyl-1,3,4-oxadiazoles

Abstract5-Trimethylsilylethynyl-2-R-1,3,4-oxadiazoles were synthesized for the first time by intramolecular cyclocondensation of unsymmetrical N-acyl-N-(3-trimethylsilyl-2-propynoyl)hydrazines by the action of phosphoryl chloride.

Sulfonylimines of Polychloroaldehydes in Reaction with Thioamides

N-(2,2,2-Trichloroethylidene)- and N-(2-phenyl-2,2-dichloroethylidene)amides of aromatic sulfonic acids react with thioacetamide, thiourea, and N-acetylthiourea at equimolar reagents ratio to furnish N-(1-arenesulfonamido-2,2,2-trichloroethyl)- and N-(1-arenesulfonamido-2-phenyl-2,2-dichloroethyl)thioamides. The reaction with deficient amount of thiourea results in N,N-bis(1-arenesulfonamido-2-polychloroethyl)-thiocarbamides.

Interaction of heteroatom-containing propynals with S-, N-binucleophiles

Reactions of α-silicon-and α-germanium-containing acetylenic aldehydes with 2-aminoethanethiol, ethylenediamine, and 2-amino-1,2,4-triazole proceed chemoselectively at the aldehyde group. The ratio of tautomers, azomethine and 1,3-thiazolidine, on interaction with 2-aminoethanethiol depends significantly on the nature of the heteroatom at the triple bond of the aldehyde, the presence of a catalyst, and the use of microwave activation.

Synthesis and structure of 4-trifluoromethylsulfonamidotrichloroethyl-5-chloropyrazoles

Reactions of trifluoromethanesulfonic acid N-(2,2,2-trichloroethylidene)amide with 1,3-dialkyl-5-chloropyrazoles and 1-phenyl-3-methylpyrazole afforded 4-(amidotrichloroethyl)-substituted pyrazole derivatives. 4-Chloropyrazoles were not involved into this process. The structure of compounds synthesized was studied by means of IR and NMR spectroscopy. The presence of intra- and intermolecular hydrogen bonds was revealed by a decrease in the absorption frequencies and a complicated form of ν(NH) and νas(SO2) absorption bands in the IR spectra, and also in splitting of signals in 1H and 13C NMR spectra.

Reaction of 3-trimethylsilylprop-2-ynal with α-hydroxyamino oximes

Abstract3-Trimethylsilylprop-2-ynal reacted with aliphatic α-hydroxyamino oximes in a chemoselective fashion at the aldehyde group to give hitherto unknown open-chain 3-trimethylsilylprop-2-yn-1-ylideneamine oxides. The possibility for intramolecular hydrogen bonding with participation of OH, C≡C, and N→O groups in the products was studied by IR spectroscopy.

Reaction of 2-Alkoxypropenals with α-Hydroxyamino Oximes and 1,2-Bis(hydroxyamino)cyclohexane

Reactions of 2-alkoxypropenals with α-hydroxyamino oximes in neutral medium involve the aldehyde group of the former to afford both acyclic and cyclic azomethine oxides: N-(2-hydroxyiminoalkyl)-N-(2-alkoxy-2-propenylidene)amine oxides and 1-hydroxy-2,5-dihydroimidazole 3-oxides. The state of tautomeric equilibrium between the cyclic and acyclic products depends on the solvent nature and temperature. The reaction in acidic aqueous medium is accompanied by hydrolysis of the vinyl ether moiety in 2-alkoxy-propenals with formation of 2-oxopropionaldehyde which reacts with α-hydroxyamino oxime at the hydroxy-amino group to give substituted pyrazine 1,4-dioxides. The reaction of 2-alkoxypropenals with 1,2-bis-(hydroxyamino)cyclohexane leads to formation of 2-(1-alkoxyvinyl)-1,3-dihydroxyperhydrobenzimidazoles. The structure of the products was proved by IR, UV, and 1H and 13C NMR spectroscopy and X-ray analysis.

Oxidation of 2-chloro-1-phenylethane-1,1-dithiol

Oxidation of 2-chloro-1-phenylethane-1,1-dithiol with bromine, iodine, and elemental sulfur, as well as under UV irradiation, leads to formation of 1,4-bis(chloromethyl)-1,4-diphenyl-2,3,5,6-tetrathiane in 50–95% yield. Oxidation of the same substrate with selenium dioxide gives 1,5-bis(chloromethyl)-1,5-diphenyl-2,4-dithia-3-selenapentane-1,5-dithiol. On heating to 60°C, the latter loses selenium to afford 1,4-bis-(chloromethyl)-1,4-diphenyl-2,3-dithiabutane-1,4-dithiol.

Reactions of heterocumulenes with organometallic reagents. IX. Synthesis and rearrangements of N-allyl- and N-[2-(vinyloxy)ethyl]-3-butenethioamides and-1-(methylsulfanyl)-3-buten-1-imines

Reactions of allyl and 2-(vinyloxy)ethyl isothiocyanates with alyylmagnesium bromide (THF-Et2O, 20-30°C, 1-3 h) after hydrolysis or alkylation of adducts afforded respectively N-allyl- and N-[2-(vinyloxy)ethyl]-3-butenethioamides or N-allyl- and N-[2-(vinyloxy)ethyl]-1-(methylmercapto)-3-buten-1-imines. The reaction carried out in ethyl ether yielded instead of Nt-allyl-3-butenethioamide its isomer N-allyl-2-butenethioamide that cleanly isomerized in the system KOH-DMSOH2O into N-(1-propenyl)-2-butenethioamide. N-[2-(vinyloxy)ethyl]-3-butenethioamide suffers a prototropic rearrangement into N-[2-(vinyloxy)ethyl]-2-butenethioamide only in the system

Reactions of Heterocumulenes with Organometallic Reagents: VIII. Reactions of Carbanions Derived from Alkoxy- and Alkylsulfanylethenes with Isothiocyanates-A Convenient Route to 2-Propenethioamides, 1-Methylsulfanyl-2-propen-1-imines, and Benzothiazoles

Abstract>Metalated alkoxy- and alkylsulfanylethenes readily add to isothiocyanates; the subsequent hydrolysis or alkylation of the adducts leads to formation of 2-propenethioamides or 1-methylsulfanyl-2-propen-1-imines (as mixtures of synand antiisomers) in 74-100% yield. The reaction of metalated alkoxyethenes with 2-fluorophenyl isothiocyanate opens the way to new benzothiazole derivatives. Hydrolysis of the latter provides a simple method for the preparation of 2-benzothiazolyl ketones.