Angelina N. Kravchenko

Neuroprotective Activity of (+)-(S)-2-[(1S,5R)-(3,7-Dioxo-2,4,6,8-Tetraazabicyclo[3.3.0]oct-2-yl)]-4-methylthiobutanoic acid

A study of the neurotropic, neuroprotective, and antioxidant action of the enantiomers and racemate of 2-[(3,7-dioxo-2,4,6,8-tetraazabicyclo[3.3.0]oct-2-yl)]-4-methylthiobutanoic acid synthesized in a stereoselective reaction of (R)-, (S)-, or (R,S)-N-carbamoylmethionine with 4,5-dihydroxyimidazolidine-2-one showed that only (+)-(S)-2-[(1S,5R)-(3,7-dioxo-2,4,6,8-tetraazabicyclo[3.3.0]oct-2-yl)]-4-methylthiobutanoic acid had neuroprotective properties. X-ray structure analysis showed that the predominating racemate of glycolurils is crystallized from aqueous solutions as a conglomerate. Antioxidant activity was not detected.

Synthesis of 2-monofunctionalized 2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-diones

New (1R*,5S*)-2-R-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-diones containing the terminal carboxy or hydroxy group in the substituent R were synthesized by cyclocondensation of 4,5-dihydroxyimidazolidin-2-one with 1-R-ureas. Single-crystal X-ray diffraction analysis showed that 2-carboxyethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione crystallizes as a racemate.

α-Thioureidoalkylation of functionally substituted ureas: I. Tandem cyclization and esterification in reactions of N-(carboxyalkyl)ureas with 1,3-dialkyl-4,5-dihydroxy-4,5-diphenylimidazolidine-2-thiones in alcohols

Acid-catalyzed reactions of N-(carboxyalkyl)ureas with 1,3-dialkyl-4,5-dihydroxy-4,5-diphenylimidazolidine-2-thiones in methanol or propan-2-ol led to the formation of previously unknown ω-(4,6-dialkyl-2-oxo-3a,6a-diphenyl-5-thioxooctahydroimidazo[4,5-d]imidazol-1-yl)alkanoic acids and their methyl and isopropyl esters. The structure of some esters was proved by X-ray analysis. Methyl (4,6-diethyl-2-oxo-3a,6adiphenyl-5-thioxooctahydroimidazo[4,5-d]imidazol-1-yl)acetate showed anxiolytic effect.

Ring contraction of 1,2,4-triazine derivatives in the synthesis of imidazoles

The review systematizes the data on the reactions of 1,2,4-triazines proceeding with a triazine ring contraction to the imidazole one. Imidazole derivatives are obtained upon treatment of 1,2,4-triazines of different saturation degree with reducing agents, oxidants, acids, as well as with the agents initiating tandem reactions, the last step of which is a triazine ring contraction, for example, nitrosating and aminating agents, organometallic compounds and aromatic aldehydes.

Diastereoselective synthesis of 4,5-dihydroxyimidazolidin-2-ones (-thiones) and their structure

Studies on the synthesis of 4,5-dihydroxyimidazolidin-2-ones (-thiones) based on the condensation of ureas or thioureas with glyoxal or 1,2-dioxo-1,2-diphenylethane showed high diastereoselectivity in the formation of racemates (trans-diastereomers) of 4,5-dihydroxyimidazolidin-2-ones (-thiones) and meso-forms (cis-diastereomers) of 4,5-dihydroxy-4,5-diphenyl-1,3-dialkylimidazolidine-2-thiones; plausible mechanisms of their formation were suggested. X-ray diffraction studies confirmed structures of diastereomers for separate examples of racemates and meso-forms of 4,5-dihydroxyimidazolidin-2-ones (-thiones).

Crystal structure, IR and 1H NMR spectra of tetranitratobis μ-(2,4,6,8-tetraethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione-O,O′)]diethanolodicadmium

The crystal structure of [Cd2(μ-BC)2(NO3)4(EtOH)2] (I), where BC is C12H22N4O2 (bicaret), has been determined. The crystals are composed of dimeric centrosymmetrical molecules. The cadmium coordination polyhedron is a trigonal bipyramid. Bicaret is a bidentate bridging ligand coordinated to the metal through two oxygens of the carbonyl groups. The IR and 1H NMR spectra of I are studied and interpreted.

An effective one-pot access to polynuclear dispiroheterocyclic structures comprising pyrrolidinyloxindole and imidazothiazolotriazine moieties via a 1,3-dipolar cycloaddition strategy

An effective and highly regio- and diastereoselective one-pot method for the synthesis of new polynuclear dispiroheterocyclic systems with five stereogenic centers (dispiro[imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-6,3′-pyrrolidine-2′,3′′-indoles]) comprising pyrrolidinyloxindole and imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine moieties has been developed. The method relies on a 1,3-dipolar cycloaddition of azomethine ylides generated in situ from isatin derivatives and sarcosine to 6-benzylideneimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7-diones.

Synthesis of imidazo[4,5-e]thiazolo[2,3-c]-1,2,4-triazine-2,8-diones via a rearrangement of imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7-diones in the reaction with isatins

An aldol condensation/skeletal rearrangement protocol for the synthesis of 1,3-dialkyl-7-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-1,3a,4,9a-tetrahydroimidazo[4,5-e]thiazolo[2,3-c]-1,2,4-triazine-2,8(3H,7H)-diones in good to high yields via a one-pot reaction of 1,3-dialkyl-3,3a,9,9a-tetrahydroimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7(1H,6H)-diones and 1H-indole-2,3-diones (isatins) or through the generation and rearrangement of 1,3-dialkyl-6-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-3,3a,9,9a-tetrahydroimidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7(1H,6H)-diones has been developed.

Methods for the synthesis of 1-substituted 1H-imidazol-2(3H)-ones

Generally applicable methods for the synthesis of 1-substituted 1H-imidazol-2(3H)-ones reported from 1923 to 2014 have been reviewed and presented to the attention of chemists in various fields.

Regioselective Synthesis of 1,5-Diaryl-2-(Hydroxyalkyl)-8-Methylglycolurils

The cyclocondensation of N-methylurea with derivatives of tetrahydroimidazooxazolone, tetrahydro-imidazooxazinone, dihydroimidazooxazinone, and tetrahydroimidazooxazepinone was studied for the first time. It was shown that the reactions take place with high regioselectivity, are regular in character, and lead to the formation of previously inaccessible 1,5-diaryl-2-(hydroxyalkyl)-8-methylglycolurils with high yields.