Cyclization reactions 31. Synthesis of 2-methyl-2-halomethylbenzimidazo [2,1-b]thiazolidinium salts and their conversions to N-(2-methyl-2,3-epithio-propyl)benzothiazol-2-ones

In a novel synthesis, from 2-methyl-2-halomethylbenzimidazo[2,1-b]thiazolidinium salts, by means of their recyclization under the influence of alkali, N-(2-methyl-2, 3-epithiopropyl)benzimidazol-2-ones have been obtained. Syntheses of the indicated salts from N-methallylbenzimidazole-2-thiones are described.Institute of Physical Organic Chemistry and Coal-Tar Chemistry, Academy of Sciences of the Ukraine, Donetsk 3400114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 706–710, May, 1994. Original article submitted May 4, 1994.     

Recyclization of 1,3,4-Oxadiazoles and Bis-1,3,4-oxadiazoles into 1,2,4-Triazole Derivatives. Synthesis of 5-Unsubstituted 1,2,4-Triazoles

Efficient methods have been developed for obtaining precursors of stable carbenes, viz. 5-unsubstituted 3,4-diaryl-1,2,4-triazoles and 3,3′- or 4,4′-bridge linked bis-1,2,4-triazoles, by the recyclization of 5-unsubstituted 1,3,4-oxadiazoles or p-phenylenebis-1,3,4-oxadiazole with anilines or aromatic diamines in the presence of trifluoroacetic acid or with aniline hydrochlorides in pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1026–1032, July, 2005.     

Stable carbenes. Synthesis and properties of benzimidazol-2-ylidenes

A new stable crystalline carbene, 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, was synthesized by decomposition of 1,3-bis(1-adamantyl)-2,3-dihydro-1H-benzimidazol-2-ylacetonitrile on heating under reduced pressure. Heteroaromatic 1,3-R₂-disubstituted benzimidazol-2-ylidenes, both stable (R = 1-Ad) and generated in situ (R = Me, Bzl), as well as 1,3,4,5-tetraphenylimidazol-2-ylidene (generated in situ), reacted with acetonitrile to give the corresponding insertion products, 1,3-disubstituted 2-cyanomethyl-2,3-dihidro-1H-(benz)-imidazoles. The geometric parameters of 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, determined by X-ray analysis, suggest its lower aromaticity as compared to imidazol-2-ylidenes and 1,2,4-triazol-5-ylidenes. The structures of 2-cyanomethyl-2,3-dihydro-1H-benzimidazoles, 2-cyanomethyl-1,3,4,5-tetraphenyl-2,3-dihydro-1H-imidazole, and 1-(1-adamantyl)-5-cyanomethyl-3,4-diphenyl-4,5-dihydro-1H-1,2,4-triazole are characterized by partial conjugation in the heteroring; some compounds exhibit luminescence under UV irradiation. 1,3-Bis(1-adamantyl)benzimidazol-2-ylidene reacted with molecular sulfur in benzene to give 1,3-bis-(1-adamantyl)-2,3-dihydro-1H-benzimidazole-2-thione, but it failed to react with selenium under analogous conditions.     

Effect of the Structure of Phase-Transfer Catalyst on the Rate of Alkaline Hydrolysis of N-Benzyloxycarbonylglycine 4-Nitrophenyl Ester in the System Chloroform-Borate Buffer

Onium salts QZ (Z = Cl, Br) having a lipophilic (Q = R₃NR', where R' = C₁₆H₃₃) or readily extractable (into organic phase) cation (Q = Ph₄P) exhibit a high catalytic activity in phase-transfer alkaline hydrolysis of N-benzyloxycarbonylglycine 4-nitrophenyl ester in the two-phase system chloroform-borate buffer (pH 10). No catalytic effect is observed in the presence of hydrophilic ammonium salts [Et₄NCl, Et₃PhCH₂NCl, Me₂(NH₂)+NCH₂CH₂+N(NH₂)Me₂·2Br^-] and those insoluble in organic solvents [(Me)₃+NNH(CH₂)₂COO^-·2H₂O, Me₂(NH₂)+NCH₂CO^-, Me₂(NH₂)+N(CH₂)₃SO₃ ^-]. These data suggest extraction mechanism of the process. The activity of lipophilic cation Q is determined mainly by two factors: its extractibility, on the one hand, and the ability to form micelles, on the other.     

Dispersion laws of hot holes in silicon

All possible exact and main approximations for decoupling the Kane equation into three linear or into a linear and a quadratic equation have been studied in the energy region E Eg. As a result of the study, a convenient analytical solution to this equation has been obtained in the plane (110), as well as approximate analytical solutions in the vicinity of <100> and <111> axes. Results obtained are also valid for other crystals with the diamond and sphalerite structure, which have the region E Eg.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 74–78, April, 1986.     

Heterocyclization of 2-allylthiobenzimidazoles into derivatives of benzimidazo[2,1-b]-1,3-thiazines

It was found that bromination of 2-allylthiobenzimiduzoles in organic solvents forms products of addition of bromine to the olefin bond-2, 3-dibromopropylthiobenzimidazoles, which spontaneously or on heating cyclize into 3-bromobenzimidazo[2,1-b]-1, 3-thiazines or cyclodehydrobromination products — 2H- or 4H-benzimidazo[2,1-b]-1, 3-thiazines.Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences of the Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 410–415, March, 1995. Original article submitted December 12, 1994.     

Adamantylation of Imidazoles and Benzimidazole

For the first time is reported on substitution of a hydrogen atom in position 4 of the imidazole ring with an aliphatic substituent occurring in reaction between 1-bromoadamantane and imidazoles. The reaction proceeds alongside the substitution in position 1 at heating in excess imidazole. In o-dichlorobenzene solution adamantylation of benzimidazole afforded 1-(1-adamantyl)benzimidazole and 1,3-di(1-adamantyl)benzimidazolium bromide. The specific features of the reactions course are described. The structure of compounds obtained is proved by ¹H NMR spectroscopy.     

Synthesis of new 1,3-thiazole derivatives from 2(5)-hydroxyalkyl-1,3-thiazole-5(2)-carbaldehydes

Reactions of substituted 2-hydroxyalkyl-1,3-thiazole-5-carbaldehydes and 5-hydroxyalkyl-1,3-thiazole-2-carbaldehydes with phenylhydrazine, isoniazid, N-substituted rhodanines were performed as well as Biginelli reaction with acetoacetic ester and urea. As a result, new 1,3-thiazole derivatives were obtained. They are of interest as potential bioactive substances.