Volume 53, Nº 5 (2017)

Proceeding from TeCl₄ and 1-octene a regioselective method was developed of the synthesis of trichloro(2-chlorooctyl)tellane. At adding methanol to this compound chlorine was easily replaced at room temperature by a methoxy group affording trichloro(2-methoxyoctyl)tellane. The reaction of TeBr₄ with 1-octene in methanol resulted in tribromo(2-methoxyoctyl)tellane. A reduction of trichloro- and tribromo(2-methoxyoctyl)tellanes occurs the most selectively in the system NaBH4–water–THF giving 1,2-bis(2-methoxyoctyl)ditellane. The reactions are characterized by a high selectivity and quantitative yields of the products.

Aiming at purposeful designing new conformationally labile bromantane analogs we performed experimental and theoretical evaluation of the basicity of new and formerly prepared compounds of this series. The connection was established between the chemical structure and the basicity of compounds obtained and preferred structures were determined for subsequent biological investigations.

Substitution of the nitro group for methyl in the position 4 of the picrylic fragment of 1-(2,4,6-trinitrophenyl)-2,2-diphenylhydrazyl increases the relative stability of hydrazyl radical in reaction with CH-acids. The reaction rate of 1-(2,4,6-trinitrophenyl)-2,2-diphenylhydrazyl with acetylacetone and ethyl acetoacetate is described with equations of first order with respect to the radical and the СН-acid and is determined by the energy of electron transfer from HOMO of СН-acid on LUMO of the radical, which is its acceptor.

Reaction of 2-chloropyridine-3,4-dicarbonitriles with primary amines in the presence of potassium carbonate in ethanol results in the fusion of pyrrole cycle and the formation of N¹-substituted 4-halo-1H-pyrrolo-[3,4-c]pyridine-1,3(2H)-diimines.

Products of allyl isothiocyanate addition to methylene active compounds, salt-like N-allyl-N,S-ketenacetals or N-allylthioamides, react with iodine, bromine or N-bromosuccinimide with the formation of derivatives of 2-ylidene-5-halomethylthiazolidines. A dependence was found of isomeric composition of obtained thiazolidines on the solvent nature.

Alicyclic 1,5,9-triketones with various combination of 5-, 6-, 7-membereded cycles in the molecule were obtained by methods of diketone condensation, Michael reaction, and proceeding from Mannich mono- and bisbases and cycloalkanones. The latter method was accompanied with a transaminomethylation, observed for the first time at triketones preparation. The structures of cyclic forms of Michael reaction products were refined.

Reaction of 3-aryl-2-bromopropanoic acids esters, products of the Meerwein arylation, with sodium azide afforded alkyl 2-azido-3-arylpropanoates. The latter react with ethyl acetoacetate and phenylacetylene to form 1,2,3-triazole derivatives. A one-pot method for the synthesis of 3-aryl-2-(4-phenyl-1H-1,2,3-triazol-1-yl)-propanoic acid esters via a tricomponent reaction of alkyl 2-bromo-3-arylpropanoates, sodium azide, and phenylacetylene in the presence of CuI was developed.

1-Amino-2-hydrazinobenzimidazole when treated with carbon disulfide underwent a regioselective cyclization involving the hydrazino group to form 9-amino-2,9-dihydro-3Н-[1,2,4]triazolo[4,3-а]benzimidazole-3-thione. Being an N-amine this compound gives Schiff bases with aromatic aldehydes, and as thione in DMF at a temperature not exceeding 60°С it is successfully alkylated, particularly by functionalized alkylating agents, affording the corresponding sulfanylmethyl derivatives. In boiling DMF, as it is demonstrated by an example of benzyl chlorides, NNH₂ group also undergoes alkylation that unexpectedly results in 4-benzylidenamino-3-benzylsulfanyltriazolobenzimidazoles.

The presence of electron-donor substituents in the phenyl ring at the atom С³ of the tetrazinyl ring increases, and of electron-acceptor substituents reduces the reaction rate of 1,5-diphenyl-3-arylverdazyl radicals with СН-acids. The reaction is described with a kinetic equation of the second order with respect to verdazyl, the process rate is determined by the energy of the electron transfer from the SOMO (singly occupied molecular orbital) of the radical to the LUMO of the СН-acid.

Quantum-chemical investigation of the mechanism of reaction between 2-methylimidazole and 1,7-diiodo-2,2,6,6-tetramethyl-2,6-disilaheptane by the method B3LYP/6-311G(d,p) provided thermodynamic and kinetic characteristics of the formation channels of the new organosilicon fused and cyclophane structures whose yield depended on the ability of iodomethyl groups to be reduced at the action of HI formed in situ. On adding iodine that initiated the formation of triiodide anions the cyclic structures were stabilized as ionic liquids.

In reaction of methyl (Е)-3-(methoxycarbonyl)methylimino-2,2-dimethylpropanoate with enolate of ethyl 3-hydroxybutanoate an abnormal reaction product was isolated, 2-methyl 4-ethyl-(2S*,3S*,4S*,5S*)-3-methyl-5-(2-methyl-1-methoxy-1-oxopropan-2-yl)pyrrolidine-2,4-dicarboxylate.

(Z)-4-Aryl-N-[2-(2-hydroxymethyl)phenyl]-2,4-dioxo-3-[3-oxo-3,4-dihydroquinoxalin-2(1Н)-ylidene]butanamide heated in Dowthem A at 200°С quickly underwent cyclization into 3а-aryl-2-hydroxy-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)-3a,5-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]oxazin-1-ones.

Opportunities were outlined for application of available KF as a source of fluoride ions and a base in desilylation/the Sonogashira coupling reactions under conditions of a one-pot process.

Reaction of aroylhydrazides with 2,4,6-trimethylbenzoyl chloride in the presence of Et₃N afforded N-(mesityl)aroylhydrazides, which through subsequent cyclization at treatment with SOCl₂ resulted in 2-aryl-5-(2,4,6-trimethylphenyl)-1Н-1,3,4-oxadiazoles. For 2-hydroxyphenyl derivative containing a stable O–H N intramolecular bond a low quantum luminescence yield is observed (φ 0.006–0.038) due to the nonradiative deactivation of the agitated state by ESPIT mechanism.