Volume 52, Nº 7 (2016)

The compositions of aqueous 2-aminoethanol solutions used in industry for absorption of carbon dioxide resulting from combustion of natural gas have been determined by ¹H and ¹³C NMR spectroscopy. The absorption process does not involve generally accepted paths of thermal decomposition of the absorbent in the reaction with carbon dioxide, but the main path is non-oxidative decomposition of 2-aminoethanol into ammonia and ethylene oxide. Splitting of the NMR signals of carbamate anion formed by reaction of 2-aminoethanol with carbon dioxide has been rationalized by specific structure of the anion due to intramolecular hydrogen bonding.

New 4-(cinnamoyloxyimino)cyclohexa-2,5-dien-1-ones were synthesized, and their bromination afforded bromine addition products to the syn- and anti-C=C bonds of the quinoid ring. In all cases, bromine addition to the C=C double bond of the cinnamoyl fragment was observed.

Functionalized β-lactams were synthesized by reaction of (E)-1-(furan-2-yl)-N-[(4-methoxyphenyl)-methyl]methanimine with ketenes generated in situ from chloro- and dichloroacetic acids and 3-(methoxyimino) butanoic acid. (E)-1-(Furan-2-yl)-N-[(4-methoxyphenyl)methyl]methanimine underwent imine–imine rearrangement by the action of potassium hydride to give thermodynamically more stable (E)-N-[(furan-2-yl)-methyl]-1-(4-methoxyphenyl)methanimine.

A procedure has been developed for the synthesis of methyl 6-alkyl-3-cyano-2-halopyridine-4-carboxylate by three-component reaction of 4-oxoalkane-1,1,2,2-tetracarbonitriles with hydrogen halides in methanol.

Removal of the acetonide protection in the synthesis of 7,8-epimer of eleutheside is accompanied by intramolecular cyclization with the formation of 15-oxatricyclo[9.3.1.0^3,8]pentadeca-5,9,12-triene tricyclic system.

Intramolecular cyclization of 4-aryl-N-(thiophen-3-yl)but-3-enamides on heating in polyphosphoric acid afforded 8-aryl-4,6,7,8-tetrahydro-5H-thieno[3,2-b]azepin-5-ones and 5-aryl-1-(thiophen-3-yl)pyrrolidin-2-ones. Cyclofunctionalization of the title compounds with (chlorosulfanyl)benzene and 4-(chlorosulfanyl)-toluene led to the formation of 8-aryl-7-arylsulfanyl-4,6,7,8-tetrahydro-5H-thieno[3,2-b]azepin-5-ones or their mixtures with 5-aryl-4-arylsulfanyltetrahydrofuran-2-ones. 1-(Chlorosulfanyl)-4-nitrobenzene reacted with 4-(4-methylphenyl)-N-(thiophen-3-yl)but-3-enamide and 4-(4-fluorophenyl)-N-(thiophen-3-yl)but-3-enamide to give 5-(4-methylphenyl)-4-(4-nitrophenylsulfanyl)-1-(thiophen-3-yl)pyrrolidin-2-one and 5-(4-fluorophenyl)-4-(4-nitrophenylsulfanyl)tetrahydrofuran-2-one, respectively.

The formation of macrocyclic polysiloxane system containing a benzimidazole fragment by reaction of benzimidazole with 1,3-bis(iodomethyl)-1,1,3,3-tetramethyldisiloxane was studied at the B3LYP/6-31G(d,p) level of theory. The calculations showed that expansion of siloxane ring involves thermodynamically controlled insertion of four silanone molecules generated by thermal decomposition of the complex derived from the initial siloxane and hydrogen triiodide.

The reactions of benzene-1,2-diamine with 5-substituted 2-(alkylsulfanyl)-4-methylpyrimidin-6(1H)-ones and 2-(propylsulfanyl)- and 5-iodo-2-(propylsulfanyl)-3,4-dihydroquinazolines at 175–185°C under solvent-free conditions unexpectedly afforded benzo[4,5]imidazo[1,2-a]pyrimidine, benzo[4,5]imidazo[2,1-b]-quinazoline, and 2,2′-(benzene-1,2-diyldiimino)bis[pyrimidin-4(3H)-ones]. The described reaction is the first example of synthesis of these heterocyclic systems by fusion of benzimidazole to pyrimidine or quinazoline and is likely to follow ANRORC mechanism.

Three-component condensation of N-aryl- and N,N-diethyl-3-oxobutanamides with salicylaldehyde and thiourea in ethanol in the presence of sodium hydrogen sulfate afforded N-aryl- and N,N-diethyl-9-methyl-11-sulfanylidene-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene-13-carboxamides. Reaction of the same compounds in the absence of a catalyst under solvent-free conditions gave N-aryl-6-(2-hydroxyphenyl)-4-methyl-2-sulfanylidene-1,2,3,6-tetrahydropyrimidine-5-carboxamides.

Three-component heterocyclizations of trifluoro-N-(prop-2-yn-1-yl)methanesulfonamide, trifluoro-N-pheny-N-(prop-2-yn-1-yl)methanesulfonamide, and trifluoro-N,N-di(prop-2-yn-1-yl)methanesulfonamide with formaldehyde and sodium azide afforded N-{[2-(hydroxymethyl)-2H-1,2,3-triazol-4-yl]methyl}-, N-{[2-(hydroxymethyl)-2H-1,2,3-triazol-4-yl]methyl}-N-phenyl-, and N,N-bis{[2-(hydroxymethyl)-2H-1,2,3-triazol-4-yl]methyl}trifluoromethanesulfonamides as the major products together with minor 1-(hydroxymethyl)-1H-1,2,3-triazole isomers.

The synthesis of N-(oxiran-2-ylmethyl)-5-phenyltetrazole was optimized, and its reactions with various nitrogen nucleophiles afforded bicyclic amino alcohols, including those containing an azole ring.

3′H-Cyclopropa[1,9](C₆₀-I_h)[5,6]fullerene-3′-carboxylic acid can be synthesized in a good yield by cyclopropanation of fullerene C₆₀ with 2-(dimethyl-λ⁴-sulfanylidene)acetates provided that the ester residue is readily hydrolyzable in acid medium.