Synthesis of (2<Emphasis Type="Italic">S</Emphasis>,3<Emphasis Type="Italic">S</Emphasis>,4<Emphasis Type="Italic">S</Emphasis>)-2,3-<Emphasis Type="Italic">O</Emphasis>-isopropylidene-4-(methoxycarbonylmethyl)cyclopentan-1-one

(2S,3S,4S)-2,3-O-Isopropylidene-4-(methoxycarbonylmethyl)cyclopentan-1-one was synthesized starting from D-ribose through methyl (Z)-3-(5-acetyl-2,2-acetoxyacetyl-2,2-dimethyl-1,3-dioxolan-4-yl)prop-2-enoate which was subjected to cyclization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, followed by decarboxylation.     

Synthesis of ethyl (2<Emphasis Type="Italic">E</Emphasis>,4<Emphasis Type="Italic">E</Emphasis>)- and (2<Emphasis Type="Italic">E</Emphasis>,4<Emphasis Type="Italic">Z</Emphasis>)-5-chloropenta-2,4-dienoates

An efficient synthetic approach to 2E,4E and 2E,4Z isomers of ethyl 5-chloropenta-2,4-dienoate has been developed on the basis of one-pot oxidation–olefination of readily accessible (E)- and (Z)-3-chloroprop-2-en-1-ols by the action of barium manganate and ethyl (triphenyl-λ⁵-phosphanylidene)acetate.     

<Emphasis Type="Italic">S</Emphasis>-functional derivatives of 3,4-dihydro-2<Emphasis Type="Italic">H</Emphasis>-1,4-thiasilines

The first cyclic unsaturated S-functional derivatives of 4,4-diphenyl-3,4-dihydro-2H-1,4-thiasiline, S-oxide, S,S-dioxide, and S-sulfonimide, were prepared. Oxidation of the hydrolytically less stable 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline leads to the corresponding sulfoxide and sulfone along with the ring opening products, siloxanes containing the sulfoxide or sulfonyl group.     

Synthesis of <Emphasis Type="Italic">ortho</Emphasis>-carboranyl derivatives of (<Emphasis Type="Italic">S</Emphasis>)-asparagine and (<Emphasis Type="Italic">S</Emphasis>)-glutamine

(S)-Asparagine and (S)-glutamine ortho-carboranyl derivatives with free amino and carboxy groups in the α-position were synthesized. By an example of N ^γ-(1,2-dicarba-closo-dodecarboran-3-yl)-(S)-glutamine it was demonstrated that the developed synthetic approach carboranyl derivatives of amino acids allowed the preparation of optically pure isomers.     

Synthesis of diethyl [(2<Emphasis Type="Italic">S</Emphasis>,4<Emphasis Type="Italic">S</Emphasis>)-4-hydroxytetrahydrofuran-2-ylmethyl]phosphonate

A convenient method for the stereoselective synthesis of diethyl [(2S,4S)-4-hydroxytetrahydrofuran-2-ylmethyl]phosphonates was developed based on preparation of phophorylated glycol followed by its intramolecular cyclization and hydrogenation. It was shown that the nature of the hydrogenation products depends on the presence of water in the solvent.     

Reaction 5-(Arylmethylidene)pyrimidine-2,4,6(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>,5<Emphasis Type="Italic">H</Emphasis>)-triones with L-Proline and Aldehydes

Boiling in toluene of 5-(arylmethylidene)pyrimidine-2,4,6(1H,3H,5H)-triones with L-proline and aldehyde led to the formation of previously unknown substituted 1′-arylhexahydro-1H-spiro[pyrimidine-5,2′-pyrrolysine]-2,4,6(1H,3Н,5Н)-triones.     

Synthesis of <Emphasis Type="Italic">O</Emphasis>,<Emphasis Type="Italic">O</Emphasis>-Dialkyl <Emphasis Type="Italic">S</Emphasis>-(1,1-dimethyl-2-oxoethyl) dithiophosphates and their reactions with N-nucleophiles

O,O-Dialkyl S-(1,1-dimethyl-2-oxoethyl) dithiophosphates, 2-(dialkoxythiophosphorylthio)-substituted aldehydes with branched carbon groups, were obtained by hydrolysis of phosphoryl-containing iminium salts. The reaction with primary amines results in imines containing acetal group in different positions. Tri- and tetra-substituted perhydro-1,3-diazoles and oxazoles containing a phosphorus atom in the side chain were prepared by reacting the aldehydes with O,Nand N,N-dinucleophiles.     

Features of self-organization of highly dilute solutions of (<Emphasis Type="Italic">S</Emphasis>)-, (<Emphasis Type="Italic">R</Emphasis>)-, and (<Emphasis Type="Italic">SR</Emphasis>)-methionines and related carbamides and glycolurils

Aqueous solutions of (S)-, (R)-, and (SR)-methionines (1–3); carbamide (4); (S)-, (R)-, and (SR)-N-carbamoylmethionines (5–7); glycoluril (8); and glycolurils containing (S)and (R)-methionine moieties (9 and 10) kept under natural and hypoelectromagnetic conditions were studied in comparison by a complex of physicochemical methods (dynamic and electrophoretic light scattering, conductometry, pH-metry, and dielcometry). The process of selforganization and the properties of dilute solutions (1.0?10^–15–10^–1 mol L^–1) of compounds 1–10 was shown for the first time to depend substantially on the structure of the solute and configuration of methionine (Met) enantiomers. In the series 1–3, the greatest ability to self-organization is observed for solutions of (SR)-Met in which supramolecular domains (1.0?10^–5–1.0?10^–1 mol L^–1) and nanoassociates (1.0?10^–11–1.0?10^–8 mol L^–1) are formed. The formation of nanoassociates in a concentration range of 1.0?10^–12–1.0?10^–6 mol L^–1 can be responsible for the appearance of nonmonotonic concentration dependences of the physicochemical properties of solutions of N-carbamoylmethionines 5–7, whereas the physicochemical properties are more pronounced in solution of (S)-N-carbamoylmethionine 5 than in solutions of 6 and 7. The strongest influence of the configuration of the Met enantiomer on the ability of solution to self-organization was revealed in a series of glycolurils 9, 10: solutions of 9 with the (S)-Met moiety are disperse systems in which nanoassociates are formed in a range of 1.0?10^–15–1.0?10^–5 mol L^–1, whereas in solutions of 10 with the (R)-Met fragment the ability to self-organization in the low-concentration range is absent.     

Bischelated complexes of a dithiocarbazate <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">S</Emphasis> Schiff base ligand: synthesis,characterization and antimicrobial activities

The N,S bidentate proligand S-hexyl-β-N-(4-methoxybenzylidene)dithiocarbazate (HL), obtained by condensation of S-hexyldithiocarbazate with 4-methoxybenzaldehyde, has been used to synthesize six metal complexes, namely NiL₂, CuL₂, ZnL₂, CdL₂, PdL₂ and PbL₂, which have been characterized by physicochemical techniques and spectroscopic methods. Single crystal structural analyses for NiL₂, CuL₂ and PdL₂ show that these are square-planar complexes with each metal bischelated by the Schiff base in its deprotonated monoanionic form. In all three cases, the ligands show a trans configuration, although they crystallize in different space groups. All the metal complexes with the exception of the nickel derivative show a significant decrease in fluorescence intensity with respect to the free proligand HL. Free HL and all six complexes were tested for antibacterial activity against three pathogenic gram-negative organisms. The metal complexes show moderate although diverse activities; however, free HL as well as the copper(II) complex did not reveal any antibacterial activity against the tested organisms.     

Molecular structure of (4Z)-{[(1<Emphasis Type="Italic">R</Emphasis>,6<Emphasis Type="Italic">S</Emphasis>)-7,7-dimethyl-2-oxo-3-oxabicyclo [4.1.0] hept-4-en-4-yl]methylene}-2-phenyl-l,3-oxazol-5(4H)-one

The (4Z)- {[(1R, 6S)-7,7-dimethyl-2-oxo-3-oxabicyclo[4.1.0]hept-4-en-4-yl]methylene}-2-phenyl-1,3-oxazol-5(4H)-one compound is synthesized and its molecular structure is determined.     

Cyclopropanation of methyl (2<Emphasis Type="Italic">E</Emphasis>)-3-[(1<Emphasis Type="Italic">R</Emphasis>,6<Emphasis Type="Italic">S</Emphasis>)-7,7-dimethyl-2-oxo-3-oxabicyclo[4.1.0]hept-4-en-4-yl]prop-2-enoate with dichlorocarbene and diazomethane

Cyclopropanation of methyl (2E)-3-[(1R,6S)-7,7-dimethyl-2-oxo-3-oxabicyclo[4.1.0]hept-4-en-4-yl]prop-2-enoate with dichlorocarbene occurred at the endocyclic double bond, while its reaction with diazomethane in the presence of Pd(acac)₂ involved the exocyclic double bond. The resulting lactones reacted with sodium methoxide in methanol via opening of one cyclopropane fragment.     

Conformations and properties of <Emphasis Type="Italic">O</Emphasis>-Alkyl-<Emphasis Type="Italic">S</Emphasis>-(2-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dialkylamino)-ethylmethylthiophosphonates

Conformers of the biologically active compounds CH₃P(O)(OR)(SCH₂CH₂NR ₂ ^′ ), where (I) R = i-C₄H₉, R′ = C₂H₅ and (II) R = C₂H₅, R′ = i-C₃H₇, are calculated within the AM1 level of theory. The elongated and twisted forms with maximum and minimum distances between a nitrogen atom and those of a phosphorus tetrahedron, respectively, and bearing a syn and anti oriented alkoxy group relative to a phosphoryl oxygen, are studied. It is found that the differences between the energy, electronic, and geometric parameters of these forms are apparent in differences between their properties, e.g., the ability to participate in complexation and protonation, reactions that to some extent simulate the interaction between a substance and a biological object.     

Stereoselective synthesis of (<Emphasis Type="Italic">Z</Emphasis>,<Emphasis Type="Italic">E</Emphasis>)-bis(2-chloroethenyl)tellanes

A procedure for the stereoselective synthesis of dichloro[(Z)-2-chloro-2-phenylethenyl][(4E)-5- chlorooct-4-en-4-yl]-λ⁴-tellane and [(Z)-2-chloro-2-phenylethenyl][(4E)-5-chlorooct-4-en-4-yl]tellane has been developed on the basis of anti-addition of tellurium tetrachloride–phenylacetylene monoadduct to oct-4-yne.     

Cyclization of trifluoro-<Emphasis Type="Italic">N</Emphasis>-(prop-2-yn-1-yl)methanesulfonamides to <Emphasis Type="Italic">N</Emphasis>-(hydroxymethyl)-1,2,3-triazoles

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.     

Enantioselective microbial synthesis of (<Emphasis Type="Italic">S</Emphasis>)-7,8-difluoro-3,4-dihydro-3-methyl-2<Emphasis Type="Italic">H</Emphasis>-[1,4]benzoxazine

New strains of Rhodococcus erythropolis 25 and Microbacterium paraoxydans 20-11c actinobacteria were used to obtain (S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine (99.6% ee) by enantioselective microbial hydrolysis of the corresponding racemic N-acetyl derivative.     

Mononuclear cobalt (III) complexes with <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-bromobenzylamine and <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-chlorobenzylamine

Cobalt (III) complexes with N-salicylidene-2-hydroxy-5-bromobenzylamine (H₂sbba) and N-salicylidene-2-hydroxy-5-chlorobenzylamine (H₂scba), [n-(C₄H₉)₄N][Co(sbba)₂] (I) and [n-(C₄H₉)₄N][Co(scba)₂] (II), were synthesized. The crystal structure of II was determined by the single-crystal X-ray diffraction method at 90 K confirming its crystallization in the monoclinic space group P2₁/n with a = 11.729(2) Å, b = 16.901(3) Å, c = 21.483(4) Å, β = 98.840(4)°, V = 4208.2(14) ų, D_x = 1.295 g cm^?3, and Z = 4. The R1 [I > 2σ(I)] and wR2 (all data) values of 0.0664 and 0.1920, respectively, for all 9521 independent reflections. The compound is composed of a tetra(n-butyl)ammonium cation and an octahedral cobalt(III) complex anion with two scba^2? ligands in a meridional fashion. The electronic spectral features of I and II are consistent with the octahedral cobalt(III) ion with an N₂O₄ donor set.     

New synthesis of diterpenoid (16<Emphasis Type="Italic">S</Emphasis>)-dihydrosteviol

A new procedure has been developed for the synthesis of diterpenoid (16S)-dihydrosteviol [(16S)-13-hydroxy-ent-kauran-19-oic acid] by acid hydrolysis (0.7% hydrochloric acid) of SWETA food sweetener and subsequent reduction of the resulting mixture of caurenoids with hydrazine hydrate over Raney nickel. The molecular geometry of (16S)-dihydrosteviol, as well as of Δ¹⁵-steviol (13-hydroxy-ent-kaur-15-en-19-oic acid), was determined for the first time by X-ray analysis.     

Solution Thermodynamics of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis><Superscript>/</Superscript>-Ethylenebis-(salicylideneiminato)-diaquochromium(III) Chloride in Aqueous Dimethylsulphoxide

The densities, viscosities and refractive indices of N,N ^/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, [Cr(salen)(H₂O)₂]Cl, in aqueous dimethylsulfoxide (DMSO) with different mass fractions (w ₂ = 0.20, 0.40, 0.60, 0.80 and 1.00) of DMSO were determined at 298.15, 308.15 and 318.15 K under atmospheric pressure. From measured densities, viscosities and refractive indices the apparent molar volumes (V _φ ), standard partial molar volume (V _φ ⁰ ), the slope (S _V ^* ), standard isobaric partial molar expansibility (φ _E ⁰ ) and its temperature dependence (?φ _E ⁰ /?T) _p , the viscosity B-coefficient, its temperature dependence (?B/?T), solvation number (S _n ) and apparent molar refractivity (R _D ^φ ), etc., were calculated and discussed on the basis of ion–ion and ion–solvent interactions. These results revealed that the solutions are characterized by ion–solvent interactions rather than by ion–ion interactions and the complex behaves as a long range structure maker. Thermodynamics of viscous flow was discussed in terms of transition state theory.     

Recyclization of 1,3-dialkyl-6-nitro-1<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridine-2,5(3<Emphasis Type="Italic">H</Emphasis>,4<Emphasis Type="Italic">H</Emphasis>)-diones into imidazole derivatives

Treatment of 5-amino-1,3-dialkyl-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones with sodium nitrite in aqueous HCl gave 1,3-dialkyl-1H-imidazo[4,5-b]pyridine-2,5(3H,4H)-diones which were nitrated with potassium nitrate in sulfuric acid to 6-nitro derivatives, and the latter underwent recyclization into 4-amino-1,3-dialkyl-5-(1H-pyrazol-5-yl)-2,3-dihydro-1H-imidazol-2-ones by the action of hydrazine hydrate.     

Cycloascauloside b from <Emphasis Type="Italic">Astragalus caucasicus</Emphasis>

The structure of a new cycloartane glycoside isolated from leaves of Astragalus caucasicus Pall. (Leguminosae) was elucidated using chemical transformations and spectral data. Cycloascauloside B is 20R, 25-epoxy-24S-cycloartan-3β,6α,16β,24-tetraol 3-O-[α-L-rhamnopyranosyl-(1å2)]-β-D-glucopyranoside.