T. N. Komarova

Synthesis of 1,3-Dialkylimidazolium and 1,3-Dialkylbenzimidazolium Salts

A number of N-alkylimidazoles and N-alkylbenzimidazoles were synthesized by reactions of imidazole and benzimidazole with alkyl halides. The reaction rate increases by a factor of 2 to 3 under conditions of microwave activation. Subsequent treatment of the resulting N-alkylazoles with alkyl halides afforded the corresponding 1,3-dialkylimidazolium and 1,3-dialkylbenzimidazolium halides.

Studies of phosphorylation reaction of tertiary amines by NMR spectroscopy

Phosphorylation of tertiary amines containing at least two ethyl groups at the nitrogen atom with phosphorus pentachloride was studied. New C-chlorophosphorylated enamines were characterized by NMR spectroscopy. A scheme was suggested for the phosphorylation reaction. It was found that the presence of two aryl substituents in the molecule of tertiary ethylamine deactivated the ethyl group to block phosphorylation. Phosphorylation of N,N-diethylaniline, besides phenyl-substituted phosphorus-containing enamines, also gave phosphorylated enamines chloro-substituted in the ring. Using N-ethyl-N-methylaniline as an example, a possibility of substitution for two chlorine atoms in the PCl5 molecule with alkenyl groups was demonstrated.

Synthesis of substituted 2-amino-1,3-thiazine-6-thiones

The reaction of thiourea with l-acyl-2-bromoacetylenes in AcOH in the presence of BF3·Et2O affords 2-amino-4-phenyl(2-thienyl)-1,3-thiazine-6-thiones in high yields.

Synthesis ofN-substituted 4-benzoyl-2-iminothiazolium bromides

Substituted thioureas react with 1-bromo-2-benzoylacetylene in various solvents at 20°C to give the correspondingN-substituted 4-benzoyl-2-(R-imino)-3-R′-thiazolium bromides.

NMR study of reactions of organyltrichlorophosphonium hexachlorophosphorates with triethylamine

The reactions of trichloro(2-ethoxyethenyl)phosphonium and trichloro(styryl)phosphonium hexachlorophosphorates with triethylamine were studied by 1H, 13C, and 31P NMR spectroscopy. It was shown that phosphonyl chlorides are the primary products of the reactions. The presence of the alkoxy group in hexachlorophosphorate results in the oxidation of the PCl2 group to form phosphonyl chlorides. Diphosphorylated oxaphosphinines were synthesized.

Microwave synthesis of secondary phosphines and phosphine oxides from red phosphorus and allyl(methoxy)benzenes in KOH-DMSO

Bis[1-(methoxyphenyl)propan-2-yl]phosphines and bis[1-(methoxyphenyl)propan-2-yl]phosphine oxides were synthesized by phosphorylation of allyl(methoxy)benzenes in the system red phosphorus-KOH · 0.5 H2O-DMSO under microwave irradiation.

Synthesis and structure of silyl-substituted imidazol-2-ylidenes and their precursors

Previously unknown heterocyclic carbenes and their precursors containing a silicon atom in the side chain were prepared. Their structures were studied by multinuclear 1H, 13C, 15N, and 29Si NMR spectroscopy.

Investigation of UV spectra of isomeric nitropyrazoles by the semiempirical AM1 (CI) method

The absorption bands in the UV spectra of isomeric nitropyrazoles were assigned by the calculations in the semiempirical AMI (CI) approximation. The long-wave absorption of nitropyrazoles is caused by π→π* and η0→π* transitions. The charge-transfer band is the most intense. The π→π* transitions undergo a considerable bathochromic shift in the deprotonation. The first ionization potential (PI) of the 4-nitropyrazole anion was estimated from the empirical dependence of the energy of the excited π-state on PI of alkyl-substituted 4-nitropyrazoles. The PI of the 4-nitropyrazole anion is 3 eV lower than that of a neutral molecule. This is evidence for a substantial destabilization of the boundary β-orbital in the heterolytic cleavage of the N−H bond. The analysis of the UV and NMR spectra of 3(5)-nitropyrazole confirms the viewpoint that the 3-nitro tautomer predominates in solution.

Quinoxaline-2,3-dithiol in reactions with propargyl bromide and 1,3-dibromopropyne

Propargyl bromide with quinoxaline-2,3-dithiol in DMSO in the presence of K2CO3 affords 2,3-bis-(2-propynylsulfanyl)quinoxaline in good yield whereas in absolute methanol in the presence of sodium methoxide at 20°C a 1:2 mixture of 2,3-bis(2-propynylsulfanyl)quinoxaline and 3-(2-propynylsulfanyl)-2(1H)-quinoxalinethione is formed. Individual 3-(2-propynylsulfanyl)-2(1H)-quinoxalinethione was obtained by crystallization of this mixture from ether. The reaction of 1,3-dibromopropyne with quinoxaline-2,3-dithiol in ethanol in the presence of NaOH at heating results in 2-bromomethylidene-1,4-(3H)-dithiino[2,3-b]quinoxaline in 77% yield. Performing this reaction in methanol in the presence of sodium methoxide during long heating (16 h) led to 2,3-bis[(3-bromo-2-propynyl)sulfanyl]quinoxaline in 72% yield.

NEW FUNCTIONALIZED PYRAZOLINES FROM 1-AROYL-2-PHENYLACETYLENES AND THIOCARBONOHYDRAZIDES

The reaction of 1-aroyl-2-phenylacetylenes with thiocarbonohydrazide and benzaldehyde thiocarbohydrazone in acetic acid-water or ethanol-water systems with the reagents in an equimolar ratio leads to the selective formation of 1-carbothiohydrazinoyl-5-hydroxy-3-phenyl-5-R-2-pyrazolines. Ring-chain tautomerism involving the enamine and hydrazone forms was detected for solutions of the pyrazolines (with R = 2-thienyl) in DMSO.