Vol 53, No 11 (2017)

Dynamic NMR was applied to measuring the value ΔG^≠ characterizing the height of the barrier to the pyramidal inversion of the nitrogen atom in carbamate and thiocarbamate anions formed at the reaction of 2-aminoethanol with CO₂ and COS. The refinement was introduced in formerly suggested cyclic structures of anions containing an intramolecular hydrogen bond NH···O(S), which contradicted the found large values of the barrier of inversion (ΔG^≠ ∼ 70 kJ mol^–1). The hydrogen bond in the cyclic anions of carbamates and thiocarbamates is two-electron and three-center. Analogous cyclic structure with a multicenter hydrogen bond does not form in the case of dithiocarbamate anion that is the product of 2-aminoethanol reaction with CS₂.

Aromatic analog of retinoic acid methyl ester was prepared using a convenient prenylating agent, 3-(bromomethyl)but-3-enal diethylacetal, and Barbier reaction in the key stage of building up the carbon chain of target molecules. A version is offered of the synthesis of methylidene analog of aromatic retinoic acid.

Preparation procedure was developed for 3-formylindole-5,6-dicarbonitriles underlain by the treatment of 1-acetoxyindole-5,6-dicarbonitriles with Vilsmeier-Haack reagent; a special feature of this reaction consisted in a replacement of the OAc group for hydrogen. A probable mechanism was assumed of the formation of 3-formylindole-5,6-dicarbonitriles.

Cyclocondensation of pent-1-en-4-yn-3-one with phenylhydrazine and p-tolylhydrazine occurs at the positions 1, 3. Proceeding from the 1-aryl-3-ethynyl-4,5-dihydro-1H-pyrazoles formed in the reaction in yields up to 95% we prepared potentially biologically active isoxazole derivatives of pyrazoline. The structure of 5-[1-(4-methylphenyl)-4,5-dihydro-1H-pyrazol-3-yl]-3-phenyl-1,2-oxazole was studied by X-ray diffraction analysis.

Three-component reaction of methyl benzoylpyruvate, aromatic aldehyde, and urea in methanol in the presence of sodium bisulfate stops at the stage of the formation of nondehydrated product with a methylated tertiary hydroxy group and results in methyl 6-aryl-5-benzoyl-4-methoxy-2-oxohexahydropyrimidine-4-carboxylates.

Basing on natural amino acid L-cysteine, commercially available aliphatic aldehydes, 2-acetylsulfanylbenzoyl chloride and 2,2′-disulfandiyldibenzoyl dichloride a synthesis was developed of (2R,4R)-2-alkyl-3-(2-mercaptobenzoyl)thiazolidine-4-carboxylic acids, potential antihypertensive compounds, inhibitors of angiotensin transforming enzyme.

Regioselective reaction of 2-bromomethyl-1,3-thiaselenole with pyridine and its derivatives is followed by rearrangement with ring expansion and the formation of a bond between a nitrogen atom and a carbon in the position 2. A set of derivatives of 2,3-dihydro-1,4-thiaselenine was obtained, substituted in the position 2 by a pyridinium residue functionalized by pharmacophoric groups.

Effective one-pot synthesis of 1,2,3-triazole derivatives of maleopimaric and dihydroquinopimaric acids consists in the reaction of diterpene propargyl esters with organic azides generated in situ in the presence of СuI catalyst.

A series of 3-(2-1Н-tetrazol-5-ylethoxy- and 2-1Н-tetrazol-5-ylethoxyimino) derivatives of dammarane triterpenoids was synthesized by azidation of 3-(2-cyanoethoxy- and 2-cyanoethoxyimino)-dammaranes. The anti-influenza activity of the prepared tetrazolyldammaranes and intermediate compounds against influenza virus А H1N1 was tested. A considerable antiviral activity was observed for 20(S)-3-(2-1Н-tetrazol-5-ylethoxyimino)-25,26,27-trinor-20,24-olidedammarane (SI 26).

The reaction of tetraethyl [1,3-phenylenedi(methylene)]bis(phosphonate) with formyl derivatives of benzocrown-ethers or formyl derivatives of o-dimethoxybenzene lead to high yield formation of the respectful bis(crown ether) containing 1,3-distyrylbenzenes or tetramethoxy-substituted 1,3-distyrenebenzenes. NMR spectra and quantum-chemical calculations showed the prevalence of unsymmetrical syn/anti,(syn,anti),syn/anti-conformations in 1,3-distyrylbenzenes. 1,3-Distyrylbenzenes absorb in shorter wavelength spectral region and have a weaker fluorescence than 1,4-distyrylbenzenes. The difficulty in the electrochemical reduction of 1,3-distyrylbenzenes comparing with 1,4-distyrylbenzenes is due to a less effective conjugation system in the metaderivatives.

Glycidyl propargyl ether was prepared in 80% yield from propargyl alcohol and epichlorohydrin in a superbasic suspension NaOH–DMSO.

In reaction of diethyl [(3,5-di-tert-butyl-4-oxocyclohexa-2,5-diеn-1-ylidene)methyl]phosphonate with N¹,N¹-dimethylethane-1,2-diamine aminophosphonate was obtained that was transformed into aminium salts by reactions with halogen derivatives of hydrocarbons.

Reaction of 4-methoxy-N,N-dichlorobenzenesulfonamide with trichloroethylene and phenylacetylene underlies an effective method developed for the synthesis of highly reactive 4-methoxy-N-(2,2,2-trichloroethylidene)- and 4-methoxy-N-(2,2-dichloro)-2-phenylethylidene)benzenesulfonamides, valuable reagents for the preparation of new difficultly accessible derivatives of the sulfonamide series.

One-stage preparation method of 2-halo-6-methoxy-5,6-dihydropyridine-3,4,4(1H)-tricarbonitriles was developed, consisting in the reaction of 3,3-dialkyl-4-oxoalcane-1,1,2,2-tetracarbonitriles with hydrohalic acids in methanol.

New tetrazolyl derivatives of pyrimidine were synthesized containing various linker groups. The structure of these compounds was established by NMR spectroscopy and X-ray diffraction analysis.