New heterocyclic systems based on substituted 3,4-dihydro-1H-spiro[quinoline-2,1'-cycloalkanes]

The Stollé type reaction of 3,4-dihydro-1H-spiro[quinoline-2,1'-cycloalkane] hydrochlorides with oxalyl chloride gave 6-methyl-5,6-dihydrospiro[pyrrolo[3,2,1-ij]quinoline-4,1'-cycloalkane]-1,2-diones, which were used in cyclocondensation with various 1,2- and 1,3-dinucleophiles and in a three-component cyclocondensation with malononitrile (or ethyl cyanoacetate) and several carbonyl compounds with activated methylene group. © 2014 Springer Science+Business Media New York

Reaction of substituted 1-methylthio-4,5-dihydro[1,2]dithiolo[3,4-c]-quinolin iodides with arylamines. Synthesis of novel 1,2-dithiolo[3,4-c]-quinolin-1-ylidene(aryl)amines and 10-(arylimino)-7,10-dihydro[1,2]dithiolo[3,4-c]-pyrrolo[3,2,1-ij]quinoline-4,5-diones

A series of novel (8-R-7-R'-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4(2)-R"- phenyl)amines were synthesized by reaction of 4,4-dimethyl-1-methylthio-4,5-dihydro[1,2]dithiolo[3,4- c]quinolin iodides with arylamines in an efficient manner. The Stolle type reaction of the obtained compounds with oxalyl chloride gave 2-R-3-R'-10-[(4(2)-R"-phenyl)imino]-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4- c]pyrrolo[3,2,1-ij]quinoline-4,5-diones. The structure of the synthesized compounds were characterized by NMR spectroscopy, mass-spectrometry and elemental analyses. © 2017 Arkat USA, Inc

Inhibition of brass (80/20) by 5-mercaptopentyl-3-amino-1,2,4-triazole in neutral solutions

The effect of the adsorption of 5-mercaptopentyl-3-amino-1,2,4-triazole (MPATA) on the corrosive behavior of brass (Cu80/Zn20) in neutral (pH 7.4) borate buffer solutions with and without 0.01 M NaCl was studied. Electrochemical methods show significant decrease of the anodic and cathodic currents on the polarization curves in the presence of MPATA. X-ray photoelectron spectroscopy (XPS) reveals MPATA adsorption on the brass surface from an inhibitor solution. After 17 h of exposure, a mixed complex [CuxZnyMPATAz] with a thickness of about 3–3.5 nm is formed on the surface. This nanolayer has sufficient protective ability to withstand corrosion tests in a salt fog chamber: after 5 days of testing, the samples remain glossy and less than 1% of the surface has been damaged. After corrosion tests in a salt fog chamber, the surface of unprotected samples is enriched with zinc, while at the surface of inhibitor-treated samples, the copper and zinc are present in practically equal contents. © 2017 by the authors. Licensee MDPI, Basel, Switzerland

Reaction of substituted 1-methylthio-4,5-dihydro[1,2]dithiolo[3,4-c]-quinolin iodides with arylamines. Synthesis of novel 1,2-dithiolo[3,4-c]-quinolin-1-ylidene(aryl)amines and 10-(arylimino)-7,10-dihydro[1,2]dithiolo[3,4-c]-pyrrolo[3,2,1-ij]quinoline-4,5-diones

A series of novel (8-R-7-R'-4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinolin-1-ylidene)(4(2)-R"- phenyl)amines were synthesized by reaction of 4,4-dimethyl-1-methylthio-4,5-dihydro[1,2]dithiolo[3,4- c]quinolin iodides with arylamines in an efficient manner. The Stolle type reaction of the obtained compounds with oxalyl chloride gave 2-R-3-R'-10-[(4(2)-R"-phenyl)imino]-7,7-dimethyl-7,10-dihydro[1,2]dithiolo[3,4- c]pyrrolo[3,2,1-ij]quinoline-4,5-diones. The structure of the synthesized compounds were characterized by NMR spectroscopy, mass-spectrometry and elemental analyses. © 2017 Arkat USA, Inc

Unexpected Reaction of Ethyl 4-(Chloromethyl)pyrazolo- [5,1-c][1,2,4]triazine-3-carboxylates with Thiourea and Its Mechanism

The reaction of ethyl 4-(chloromethyl)pyrazolo[5,1-c][1,2,4]triazine-3-carboxylates with thiourea in dimethylformamide involves ANRORC rearrangement (Addition of the Nucleophile, Ring Opening, and Ring Closure) followed by N-formylation to give N-{5-(4-oxo-8-phenyl-1,4-dihydropyrazolo[5,1-c][1,2,4]-triazin-3-yl)-1,3-triazol-2-yl}formamides whose structure was confirmed by X-ray analysis. The reaction mechanism has been studied by HPLC/MS. © 2018, Pleiades Publishing, Ltd

New heterocyclic systems based on substituted 3,4-dihydro-1H-spiro[quinoline-2,1'-cycloalkanes]

The Stollé type reaction of 3,4-dihydro-1H-spiro[quinoline-2,1'-cycloalkane] hydrochlorides with oxalyl chloride gave 6-methyl-5,6-dihydrospiro[pyrrolo[3,2,1-ij]quinoline-4,1'-cycloalkane]-1,2-diones, which were used in cyclocondensation with various 1,2- and 1,3-dinucleophiles and in a three-component cyclocondensation with malononitrile (or ethyl cyanoacetate) and several carbonyl compounds with activated methylene group. © 2014 Springer Science+Business Media New York

Unexpected Reaction of Ethyl 4-(Chloromethyl)pyrazolo- [5,1-c][1,2,4]triazine-3-carboxylates with Thiourea and Its Mechanism

The reaction of ethyl 4-(chloromethyl)pyrazolo[5,1-c][1,2,4]triazine-3-carboxylates with thiourea in dimethylformamide involves ANRORC rearrangement (Addition of the Nucleophile, Ring Opening, and Ring Closure) followed by N-formylation to give N-{5-(4-oxo-8-phenyl-1,4-dihydropyrazolo[5,1-c][1,2,4]-triazin-3-yl)-1,3-triazol-2-yl}formamides whose structure was confirmed by X-ray analysis. The reaction mechanism has been studied by HPLC/MS. © 2018, Pleiades Publishing, Ltd

Inhibition of brass (80/20) by 5-mercaptopentyl-3-amino-1,2,4-triazole in neutral solutions

The effect of the adsorption of 5-mercaptopentyl-3-amino-1,2,4-triazole (MPATA) on the corrosive behavior of brass (Cu80/Zn20) in neutral (pH 7.4) borate buffer solutions with and without 0.01 M NaCl was studied. Electrochemical methods show significant decrease of the anodic and cathodic currents on the polarization curves in the presence of MPATA. X-ray photoelectron spectroscopy (XPS) reveals MPATA adsorption on the brass surface from an inhibitor solution. After 17 h of exposure, a mixed complex [CuxZnyMPATAz] with a thickness of about 3–3.5 nm is formed on the surface. This nanolayer has sufficient protective ability to withstand corrosion tests in a salt fog chamber: after 5 days of testing, the samples remain glossy and less than 1% of the surface has been damaged. After corrosion tests in a salt fog chamber, the surface of unprotected samples is enriched with zinc, while at the surface of inhibitor-treated samples, the copper and zinc are present in practically equal contents. © 2017 by the authors. Licensee MDPI, Basel, Switzerland

A novel synthetic approach to hydroimidazo[1,5-b]pyridazines by the recyclization of itaconimides and HPLC-HRMS monitoring of the reaction pathway

The novel cascade two-stage reaction between itaconimides and 1,2-diamino-4-phenylimidazole proceeds regio- and chemoselectively to form tetrahydroimidazo[1,5-b]pyridazines and includes nucleophilic C-addition by the activated C=C double bond and subsequent intramolecular recyclization of the intermediate with the amino group involved. © 2017 Vandyshev et al.; licensee Beilstein-Institut

Synthesis of N-vinylformamide and 1-vinyl-(1-methacryloyl)-3,5-dimethylpyrazole copolymers and their extraction ability in relation to histidine in water-salt media

Copolymers of N-vinylformamide (VF) with 1-vinyl-3,5-dimethylpyrazole (VDMP) and 1-methacryloyl-3,5-dimethylpyrazole (MDMP) are synthesized by free radical copolymerization in dioxane. The compositions of copolymers are determined by means of UV-spectroscopy and FTIR, and copolymerization constants r1 and r2 are calculated. N-vinylformamide demonstrates higher reactivity than pyrazole-containing monomers in both cases. Solubility of the synthesized copolymers in water was studied. VF–VDMP copolymers are water soluble at VF content higher than 0.65 molar fractions, and VF–MDMP copolymers—at VF content over 0.8 molar fractions. The formation of complexes between water-soluble copolymers and essential α-amino acid histidine in aqueous solutions is confirmed by UV-spectroscopy, FTIR, dynamic light scattering (DLS), and transition electron microscopy. It is found via DLS that the interactions between the amino acid with copolymer macromolecules lead to conformation changes in macromolecular coils. It is shown that VF–VDMP and VF–MDMP copolymers are effective extragents for histidine. Extraction is carried out at different pH values. The highest extraction degree (98%) is achieved in an acidic medium. © 2017, Springer-Verlag GmbH Germany