Oxidation of (1<Emphasis Type="Italic">S</Emphasis>,5<Emphasis Type="Italic">R</Emphasis>,7<Emphasis Type="Italic">R,S</Emphasis>)-(4,7-dimethyl-6-oxabicyclo[3.2.1]oct-3-en-7-yl) methanol with pyridinium chlorochromate

The oxidation of (1S,5R,7R,S)-(4,7-dimethyl-6-oxabicyclo[3.2.1]oct-3-en-7-yl)methanol epimeric at the C⁷ atom resulted in scalemic (5R)-5-acetyl-2-methylcyclohex-2-en-1-one.     

Hydrogenation and conformational analysis of (1<Emphasis Type="Italic">R</Emphasis>,2<Emphasis Type="Italic">R</Emphasis>,6<Emphasis Type="Italic">S</Emphasis>)-3-methyl-6-(1-methylethenyl)cyclohex-3-ene-1,2-diol

Hydrogenation of (1R,2R,6S)-3-methyl-6-(1-methylethenyl)cyclohex-3-ene-1,2-diol was studied. Nickel chloride-sodium tetrahydridoborate system turned out to selectively reduce the double bond in the isopropenyl group. The results of conformational analysis of (1R,2R,6S)-3-methyl-6-(1-methylethenyl)cyclohex-3-ene-1,2-diol and its partly and completely hydrogenated derivatives were in a good agreement with the NMR data.     

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 (2<Emphasis Type="Italic">R</Emphasis>,4<Emphasis Type="Italic">R</Emphasis>)-2-alkyl-3-(2-mercaptobenzoyl)thiazolidine-4-carboxylic acids

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.     

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.     

Regioselectivity of the interaction of (1<Emphasis Type="Italic">S</Emphasis>,2<Emphasis Type="Italic">S</Emphasis>)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with some symmetrical ketones

The interaction of (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with a series of symmetrical ketones has been studied. As a result isomeric oxazolidines are formed in a ratio of 85:15. These oxazolidines were shown to decompose readily under the action of hydrazine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1518–1523, October, 2004.     

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.     

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.     

Crystal structure investigation of (4<Emphasis Type="Italic">S</Emphasis>,5<Emphasis Type="Italic">S</Emphasis>)-4-[(dichloroacetoxy)methyl]-5-(4-nitrophenyl)-2-oxazolidinone

The structure of (4S,5S)-4-[(dichloroacetoxy)methyl]-5-(4-nitrophenyl)-2-oxazolidinone has been determined by crystal structure investigation.     

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.     

Synthesis of chiral glycolurils from (<Emphasis Type="Italic">S</Emphasis>)-(+)- and (<Emphasis Type="Italic">R</Emphasis>)-(-)-1-<Emphasis Type="Italic">sec</Emphasis>-butyl-3-methylurea

Chiral dialkyl- and tetraalkylglycolurils have been obtained using chiral (S)-(+)- and (R)-(-)-1-sec-butyl-3-methylurea as starting materials. The diastereomer (S)-(+)-2,6-di-sec-butyl-4,8-dimethyl-2,4,6,8-tetraazabicyclo[3.3.0]-octane-3,7-dione was separated into stereoisomers, for the higher melting of which the absolute configuration was determined as (S,S,S,S) by X-ray structural analysis.     

Asymmetric hydrogen-transfer hydrogenation on rhodium(I) complexes with new optically active salen ligands derived from (4<Emphasis Type="Italic">S</Emphasis>,5<Emphasis Type="Italic">S</Emphasis>)-4,5-bis(aminomethyl)-2,2-dimethyl-1,3-dioxolane

New optically active C ₂-symmetric salen-type ligands were synthesized on the basis of (4S,5S)-4,5-bis(aminomethyl)-2,2-dimethyl-1,3-dioxolane. These ligands were used to obtain cationic (trifluoromethanesulfonate) and neutral (chloride) rhodium(I) complexes with [(4S,5S)-2,2-dimethyl-5-{[(E)-pyridin-2-ylmethylidene]aminomethyl}-1,3-dioxolan-4-yl]-N-[(E)-pyridin-2-ylmethylidene]methanamine and [2,2-dimethyl-5-{[(E)-quinolin-2-ylmethylidene]aminomethyl}-1,3-dioxolan-4-yl]-N-[(E)-quinolin-2-ylmethylidene] methanamine. The latter complex ensured preparation of (S)-2-phenylethanol with an optical yield of 34.8% by transfer hydrogenation of acetophenone.     

Diamidophosphite based on (1<Emphasis Type="Italic">R</Emphasis>,2<Emphasis Type="Italic">R</Emphasis>)-1,2-bis(3-hydroxybenzamido)cyclohexane in Pd-catalyzed enantioselective allylation

Diamidophosphite ligand bearing (1R,2R)-1,2-bis(3-hydroxybenzamido)cyclohexane fragment and stereogenic phosphorus atoms in the 1,3,2-diazaphopholidine cycles was synthesized. Catalytic performance of this ligand was evaluated in asymmetric allylic substitution. In the reactions involving (E)-1,3-diphenyl allyl acetate as a substrate, up to 94% ee in alkylation with dimethyl malonate and up to 68% ee in amination with pyrrolidine was achieved in the presence of this ligand.     

<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.     

Screening and Immobilization <Emphasis Type="Italic">Burkholderia</Emphasis> sp. GXU56 Lipase for Enantioselective Resolution of (<Emphasis Type="Italic">R</Emphasis>,<Emphasis Type="Italic">S</Emphasis>)-Methyl Mandelate

Microorganisms producing lipase were isolated from soil and sewage samples and screened for enantioselective resolution of (R,S)-methyl mandelate to (R)-mandelic acid. A strain designated as GXU56 was obtained and identified as Burkholderia sp. Preparing immobilized GXU56 lipase by simple adsorption on octyl sepharose CL-4B, the optimum temperature was shifted from 40 °C (free lipase) to 50 °C (immobilized lipase), and the optimum pH was shifted from 8.0 (free lipase) to 7.2 (immobilized lipase). The immobilized enzyme displayed excellent stability in the pH range of 5.0–8.0, at the temperatures below 50 °C and in organic solvents compared with free enzyme. Enantioselectivity ratio for (R)-mandelic acid (E) was dramatically improved from 29.2 to more than 300 by applying immobilized lipase in the resolution of (R,S)-methyl mandelate. After five cycles of use of immobilized lipase, conversion and enantiomeric excess of (R)-mandelic acid were 34.5% and 98.5%, respectively, with enantioselectivity ratio for (R)-mandelic acid (E) of 230. Thus, octyl-sepharose-immobilized GXU56 lipase can be used as a bio-resolution reagent for producing (R)-mandelic acid.     

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">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.     

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.     

Synthesis of (<Emphasis Type="Italic">E</Emphasis>)- and (<Emphasis Type="Italic">Z</Emphasis>)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles

Abstract  An efficient synthesis method for the preparation of a series of new (Z)- and (E)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles was developed. The reaction of (Z)- and (E)-3-styrylchromones with hydrazine hydrate afforded the corresponding (Z)- and (E)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles, except for nitro derivatives, where both (Z)- and (E)-4′-nitro-3-styrylchromones afforded (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles. The reaction mechanism for these transformations is discussed and the stereochemistries of all products were established by NMR experiments. Graphical abstract        

Synthesis of (<Emphasis Type="Italic">S</Emphasis>)-(-)-1,4-diaryl-6-methyl-4-trifluoromethyl-3,4-dihydropyrimidine-2(1<Emphasis Type="Italic">H</Emphasis>)-thiones

(S)-(+)-4-Amino-4-aryl-5,5,5-trifluoropentan-2-one reacted with aryl isothiocyanates containing electron-withdrawing substituents to give (S)-(−)-1,4-diaryl-6-methyl-4-trifluoromethyl-3,4-dihydropyrimidine-2(1H)-thiones.