Vol 55, No 2 (2019)

A quantum-chemical study of the reaction mechanism of 2-mercaptobenzothiazole with (iodomethyl)(dimethyl)phenylsilane in the presence of iodine was performed by the B3LYP/6-311G(d,p) method. Possible routes of formation of annulated heterocyclic systems were proposed. It was found the molecular iodine involved in the reaction has a decisive effect on the thermodynamic and kinetic characteristics of the cyclization process.

The alkylation of purine-6-thione with prenyl bromide and 3-butenyl bromide in the presence of alkali gave 6-[prenyl(but-3-enyl)sulfanyl]purines which reacted with halogens to afford fused [1,3]thiazino[2,3-i]purinium systems.

Oxidative coupling of 6,7,8,9,9a,10,11,12,13,14-decahydro-5H-benzimidazo[2,1-e]acridine with reagents containing a primary aromatic amino group forms p-quinone diimines of the 2H-benzimidazo[2,1-e]-acridine series. The subsequent acid-activated 1,4-nucleophilic addition reaction of the products with the same reagents followed by autooxidation gives rise to 3-arylamino-substituted quinone diimines of the specified series.

The reactions of alkyl 5-acetylhexahydropyrimidine-5-carboxylates with ammonia, hydrazine hydrate, and lithium aluminum hydride were used to synthesize hexahydropyrimidine derivatives containing pharmacophoric 1,3-propylenediamine and 1,3-propanolamine fragments.

N-(2-Phenyl-1-piperidin-1-ylethylidene)tosylamide was synthesized by oxidative coupling of arenesulfonamides, acetylenes, and secondary amines. The reaction of phenylacetylene or propargyl alcohol with triflamide and piperidine under the same conditions unexpectedly gave N-[(1E)-piperidin-1-ylmethylidene]triflamide TfN=CHNC₅H₁₀ as a result of cleavage of the triple bond in the alkyne. A similar reaction with benzoylacetylene gave (2E)-1-phenyl-3-piperidin-1-ylprop-2-en-1-one, while triflamide did not react. Adducts of a series of acetylenes with triflamide were obtained using triflamide sodium salt. Attempted synthesis of an N-triflyl-substituted analog of amidine 1 by the reaction of benzoylacetylene with triflamide and piperidine or morpholine in the presence of Cu(OTf)₂ and hydrogen peroxide as an oxidant unexpectedly gave 1-piperidin-1-yl- or 1-morpholin-1-ylmethanimine, respectively.

Perfluoro(alkylbenzocycloalken-1-yl) cations were generated in a SbF₅−SO₂ClF medium from perfluorinated indane and benzocyclobutene derivatives containing perfluoroalkyl groups in the alicyclic fragment. The cations exist in equilibrium with their precursors. Adding SO₂Cl₂ to the system led to the formation of polyfluoroalkylbenzocycloalken-1-yl cations with a chlorine substituent at the cationic center. The structures of the cations were determined by ¹⁹F and ¹³C NMR spectroscopy and confirmed by the structures of perfluoroketones formed on their hydrolysis.

(2E,2′E)-3,3′-(Propane-1,3-diyl)bis[oxy(4,1-phenylene)]bis[2-(4-aryl-1,3-thiazol-2-yl)acrylonitriles] and functionally substituted pyridines and fused pyrans containing a 3-[1,3-thi(selen)azol-2-yl]-substituent were synthesized by multicomponent condensations initiated by the Knoevenagel reaction. The structures of 2-amino-5-oxo-4-(1-phenylethyl)-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile and 2-amino-7-hexyloxy-4-cyclohexyl-4H-chromene-3-carborutrile were studied by X-ray diffraction analysis.

Recyclization of 4-oxo-1,3-benzoxazinium perchlorates under the action of hydrazinobenzoic acids gave previously unknown 1,2,4-triazolylbenzoic acids which were esterified to obtain the corresponding esters. Alkylation of 3-(o-hydroxyphenyl)-1,2,4-triazoles with ethyl chloroacetate formed ethyl triazolylacetates, whose aminolysis allowed synthesis of novel bis-heterocyclic imides.

In the current study, two quinazoline derivatives di-cationic surfactants, that contain long carbon chain, have been synthesized. Their structures were supported by spectroscopic methods, and their anticorrosive protection on mild steel was tested in acidic medium at room temperature for 24 h. Corrosion processes were evaluated by the gravimetric method based on the weight loss of metal plates. Fairly good corrosion inhibition efficiencies (92.44%–95.49%) were achieved at different concentrations of the inhibitors. SEM images of the metal surfaces supported the corrosion inhibition efficiency of the products.

A series of novel 4-(4-methoxyphenethyl)-3,5-disubstime-4H-1,2,4-triazoles (3) are synthesized by reacting one of hydrazonates (1) with 2-(4-methoxyphenyl)ethanamine (2). The structures of compounds 3a–3f are elucidated from IR and NMR spectra. Compounds 3b and 3d are characterized also by X-ray crystallography. DFT computations of the compounds involve Gaussian 09 software package with Gauss Viewvisualization program. In determination of geometric optimization, vibrational frequencies, chemical shift values, DFT/B3LYP method with 6-311++G(d,p) basis set is used. Newly synthesized compounds are screened for antimicrobial activity. Compounds 3c–3f containing the 4-hydroxyphenyl group demonstrate moderate antimicrobial activity.

A substituted quinoline-6-carbohydrazide was synthesized by the reaction of ethyl 4-hydroxy-2-methylquinoline-6-carboxylate with hydrazine hydrate. The quinoline-6-carbohydrazide was reacted with phenyl isothiocyanate to obtain the corresponding phenylhydrazinecarbotioamide. The intramolecular cyclization of the latter in alkaline and acidic media gave quinolyl-substituted triazole and thiadiazole. The reaction of the quinoline-6-carbohydrazide with carbon disulfide in an alkaline media yielded a quinolyl-substituted 1,3,4-oxadiazole, and the reactions of the same reagent with substituted benzaldehydes gave N′-(substituted benzylidene)quinoline-6-carbohydrazides.

The reactions of 5-(arylmethylidene)-2,4,6-pyrimidine-2,4,6(1H,3H,5H)-triones with arenecarbaldehyde phenylhydrazones in the presence of sodium N-chlorobenzenesulfonamide give 2,3,7,9-tetraasaspiro-[4.5]dec-1-ene-6,8,10-triones in yields of 30–45%.

A one-pot synthesis of 2-ylidene-1,3-dithiolanes, involving the reaction of carbon disulfide with methylene-active compounds in the presence of sodium ethylate followed by adding 1,2-dichloralkanes to the reaction mixture, is developed.

The reaction of (ethoxymethylidene)cyanoacetic ester with arylamides of acetoacetic acid proceeds under heating in the presence of triethylamine or at room temperature in the presence of sodium ethoxide. According to the NMR and IR data, the intermediate adduct undergoes no other transformations but azacyclization which predominantly involves the cyano group and forms ethyl 5-acetyl-1-aryl-6-hydroxy-2-imino-1,2-dihydropyridine-3-carboxylates in yields of 30–78%. In some cases, 5-acetyl-1-aryl-2-hydroxy-6-oxo-1,6-dihydropyridine-3-carbonitriles resulting from cyclization involving the ethoxycarbonyl group were isolated as minor products (3–12%).