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.     

Synthesis of (<Emphasis Type="Italic">E</Emphasis>)-<Emphasis Type="Italic">N</Emphasis>-(3-alkoxy-4-acyloxyphenylmethylene)-<Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">e</Emphasis>-cyclohexyl)amines

Previously unknown E isomers of azomethines (Schiff bases) were synthesized from vanillal and vanillin esters by their reaction with cyclohexylamine.     

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 <Emphasis Type="Italic">N,N</Emphasis>-disubstituted (<Emphasis Type="Italic">Z</Emphasis>)-<Emphasis Type="Italic">O</Emphasis>-methylnicotinamide oximes

A number of (Z)-N,N-dialkyl- and (Z)-N-acyl-N-alkyl-O-methylnicotinamide oximes was synthesized. Their configuration was confirmed by the NOESY experiment. Evaluation of fungicidal activity of compounds obtained was performed.     

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.     

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 <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.     

Synthetic Approaches to Physiologically Active Polycyclic Compounds: VI. Synthesis of 1-[(2<Emphasis Type="Italic">R</Emphasis>,3<Emphasis Type="Italic">S</Emphasis>)-<Emphasis Type="Italic">N</Emphasis>-Benzoyl-phenylisoseryloxy]-4,4-dimethyladamantane

A convenient procedure was proposed for the synthesis of 4,4-dimethyladamantan-1-ol from 2-adamantanone. Esterification of the product with protected amino acid gave 1-[(2R, 3S)-N-benzoylphenyl-isoseryloxy]-4,4-dimethyladamantane.     

Synthesis and crystal structure of (2<Emphasis Type="Italic">S</Emphasis>,4<Emphasis Type="Italic">S</Emphasis>,5<Emphasis Type="Italic">R</Emphasis>)-2-(5-bromo-2-hydroxyphenyl)-3,4-dimethyl-5-phenyl-1,3-oxazolidines

Condensation of ephedrine alkaloids with 5-bromo-2-hydroxybenzaldehyde was studied, and X-ray diffraction analysis of the synthesized (2S,4S,5R)-2-(2-hydroxy-5-bromophenyl)-3,4-dimethyl-5-phenyl-1,3-oxazolidines was performed.     

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.     

Heat capacities and thermodynamic properties of (<Emphasis Type="Italic">S</Emphasis>)-<Emphasis Type="Italic">tert</Emphasis>-butyl 1-phenylethylcarbamate

An N-tert-butyloxycarbonylated organic synthesis intermediate, (S)-tert-butyl 1-phenylethylcarbamate, was prepared and investigated by means of differential scanning calorimetry (DSC) and thermogravimetry (TG). The molar heat capacities of (S)-tert-butyl 1-phenylethylcarbamate were precisely determined by means of adiabatic calorimetry over the temperature range of 80-380 K. There was a solid–liquid phase transition exhibited during the heating process with the melting point of 359.53 K. The molar enthalpy and entropy of this transition were determined to be 29.73 kJ mol⁻¹ and 82.68 J K⁻¹ mol⁻¹ based on the experimental C _p–T curve, respectively. The thermodynamic functions, [H_T⁰ - H_298.15⁰ H_{T}^{0} - H_{298.15}^{0} ] and [S_T⁰ - S_298.15⁰ S_{T}^{0} - S_{298.15}^{0} ], were calculated from the heat capacity data in the temperature range of 80–380 K with an interval of 5 K. TG experiment showed that the pyrolysis of the compound was started at the temperature of 385 K and terminated at 510 K within one step.     

Synthesis and structures of benzo[<Emphasis Type="Italic">cd</Emphasis>]furo[2,3-<Emphasis Type="Italic">f</Emphasis>]indol-4(5<Emphasis Type="Italic">H</Emphasis>)-one derivatives

A procedure was developed for the synthesis of derivatives of the new heterocyclic system, benzo[cd]furo[2,3-f]indole, based on the cyclodehydration of 6-acylmethyloxy-1-alkyl-benzo[cd]indol-2(1H)-ones. Either 7- or 8-aryl derivatives of benzo[cd]furo[2,3-f]indol-4(5H)-ones can be prepared depending on the reaction conditions. The molecular and crystal structures of 7- and 8-phenylbenzo[cd]furo[2,3-f]indol-4(5H)-ones were established by X-ray diffraction.     

Reactions of 2-(2-propynylsulfanyl)-5,6,7,8-tetrahydrobenzo[<Emphasis Type="Italic">b</Emphasis>]thieno[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(<Emphasis Type="Italic">3H</Emphasis>)-one with arylsulfenyl chlorides

2-(2-propynylsulfanyl)-5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-one with arylsulfenyl chlorides in chloroform gave products of anti-Markownikoff Ad _E-addition. The use of nitromethane as solvent in the presence of lithium perchlorate additives favored intramolecular electrophilic cyclization into 1-arylsulfanyl-1,2,6,7,8,9-hexahydro-4H-benzo[4,5]thieno[3,2-e][1,3]thiazolo[3,2-a]-pyrimidin-5-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 (<Emphasis Type="Italic">S</Emphasis>)-(+)-6-aryl-3-acetyl-6-trifluoromethyl-5,6-dihydropyridin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones

(S)-(+)-4-Amino-4-aryl-5,5,5-trifluoropentan-2-ones reacted with ethyl acetoacetate and ethyl trifluoroacetoacetate to give (S)-(+)-6-aryl-3-acetyl(or trifluoroacetyl)-6-trifluoromethyl-5,6-dihydropyridin-2(1H)-ones.     

A Cuboidal Tetranuclear Nickel Cluster Based on <Emphasis Type="Italic">O</Emphasis>,<Emphasis Type="Italic">O</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Tridentate Schiff Base: Synthesis,Structure and Magnetic Properties

One tetranuclear nickel cluster [Ni₄L₄(CH₃CH₂OH)₄] (1, H₂L = N-(2-hydroxyphenyl)salicylaldimino) was synthesized by solvothermally reaction and characterized by elemental analysis, IR, TGA and X-ray single-crystal diffraction. It exhibits a cubane-type [Ni₄O₄] structure with four Schiff base ligands and four alcohol molecules in the unit. Magnetic susceptibility studies indicate that there are ferromagnetic interactions within the tetranuclear nickel(II) cluster. Furthermore, Thermogravimetric analyses display the stability of complex 1.     

Syntheses of (<Emphasis Type="Italic">E</Emphasis>)- and (<Emphasis Type="Italic">Z</Emphasis>)-3-styrylchromones

Several (E)- and (Z)-3-styrylchromones were prepared by two different methodologies, the Wittig reaction of chromone-3-carboxaldehyde with benzylic ylides and the Knoevenagel condensation of chromone-3-carboxaldehyde with phenylacetic acids in the presence of potassium tert-butoxide under microwave irradiation. The Knoevenagel reaction followed by a decarboxylation offered an efficient and diastereoselective method for preparing (E)-3-styrylchromones in a shorter reaction time. It was also demonstrated that phenylacetic acid can also be substituted with success by phenylmalonic acid. The stereochemistry of all products was assigned by NMR experiments. Correspondence: Artur M. S. Silva, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal.