Condensed heterocycles. 41. Mass spectrometric study of selenol(mercapto)aldimines of benzo[b]thiophene and their S,Se-alkyl derivatives

The production of imines of 3-selenol(mercapto)-2-benzo[b]thiophenaldehyde and 2-selenol(mercapto)-3-benzo[b]thiophenaldehyde and their S,Se-alkyl derivatives under electron impact was studied. The main distinctions of the decomposition of the molecular ions of selenium-containing compounds from their sulfur analogs, due to the greater strength of the C-S bond in comparison with the C-Se bond, were demonstrated. The different behavior of isomeric 3- and 2-mercaptoaldimines of benzo[b]thiophene was detected.For communication 40, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1057–1061, August, 1984.     

β-Benzotriazolylethyl phosphates and phosphonic esters

β-(1-Benzotriazolyl)ethyl dibutyl phosphate and the 2-benzotriazolyl analog were prepared from dibutyl phosphite and 1- and 2-(β-hydroxyethyl)benzotriazoles, respectively. Dialkyl β-(N-benzotriazolyl) ethylphosphonates were prepared from the corresponding dialkyl β-bromoethylphosphonates. In both types of compounds, elimination of benzotriazole occurs in base; interestingly, such elimination is significantly faster in each series for the 2-substituted benzotriazole than for the corresponding 1-isomer.     

Isomerization of dichloro- and difluorobenzenes: A quantum-chemical consideration

The AM-1 method with full optimization of geometry was used to study several proposed isomerization mechanisms for dichloro- and difluorobenzenes on active centers as proton donors. Preferred positions of proton addition in dihalobenzenes were studied and protonation and activation energies for intramolecular migration of hydrogen and halogen atoms were determined. It was shown that the isomerization mechanisms are the same for dichloro-and difluorobenzenes and result from a 1,2-shift of the halogen. The activation energy for migration of a fluorine atom in difluorobenzenonium cations is substantially higher than for a chlorine atom in dichlorobenzenonium cations. The data obtained on the mechanism have experimental verification.A. N. Nesmeyanov Institute Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117433 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 731–737, March, 1992.     

Acidity and catalytic activity of polyfunctional zeolite catalysts in the benzene-propene-diisopropylbenzene system

Studies on the effect of the acidity of polyfunctional zeolite catalysts on their activity in benzene alkylation by propene and its transalkylation by diisopropylbenzene (DIPB) have revealed that alkylation and transalkylation of aromatics proceed on catalytic centers of different acidity.

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Stereochemistry of electrophilic annelation of 2-allyl- (and 2-cyclohexen-1-yl)thio-1,5-naphthyridines to thiazolo]3,2-a]-1,5-naphthyridinium salts

Methods have been developed for the synthesis of 3-cyano-5,8-ethano-5,6,7,8-tetrahydro-1,5-naphthyridine-2(1H)-thione and 2-allyl- (and 2-cyclohexen-1-yl)thio-1,5-naphthyridines, and their structures have been studied. X-ray diffraction examination has shown that these compounds contain a disordered contact between the free electron pair of the pyridine nitrogen and the -bond of the allyl grouping, so that they react stereoselectively with halogens to give thiazolo[3,2-a]-1,5-naphthyridinium salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 557–563, April, 1989.