Regioselective Synthesis and Base Catalyzed Transacylation of Substituted 1H—Pyrazole—4—carboxamides

New type of substituted 1H-pyrazole-4-carboxamides were obtained by regioselective synthesis under the catalysis of different based.The stuctures of the title compounds were confirmed by elemental analysis,^1H NMR,IR,MS and X-ray crystallography.Compounds 1 were transcaylated into their corresponding.Compounds 1 were transacylated into their corresponding amides 3 in the prsence of sodium hydride.Preliminary bioassays indicated that some compounds showed fungicidal activities against Rhizoctonia solani and Sclerotinia sclerotiorum.     

Aminolysis of 2,2-difluoro-4-alkoxy-1,3,2-dioxaborinanes: route to β-keto amides and β-enamino carboxamides

4-Alkoxy substituted 1,3,2-dioxaborinanes 1, readily available from β-keto esters, undergo substitution reactions under mild reaction conditions with primary and secondary amines, deriving the 4-alkylamino analogue 2. Reactions of 1 with substituted phenylhydrazines gave the corresponding hydrazones, or pyrazolones, and 5-alkoxy-1H-pyrazoles as a mixture of products.     

(Tosylimino)phenyl-λ3-iodane as a reagent for the synthesis of methyl carbamates via Hofmann rearrangement of aromatic and aliphatic carboxamides

A new, mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides using (tosylimino)phenyl-λ(3)-iodane, PhINTs, as a reagent is reported. Because of the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides, which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates or their subsequent conversion to stable carbamates by treatment with alcohols.     

Resolution of 8′-alkoxy- and hydroxy-1,1′-binaphthalen-8-ols

Enantiopure 8′-ethoxy-, 8′-hydroxy-, and 8′-methoxy-1,1′-binaphthalen-8-ol were readily resolved by separating the corresponding chiral camphanic esters [derived from the esterification of the alcohols with (−)-(1S)-camphanic chloride] based upon their differing solubility in diethyl ether and their differing chromatographic behavior.     

Synthesis and structure of some 8α-analogs of steroid estrogens

The distances between the protons of four 8α-analogues of steroid estrogens as determined by X-ray data are consistent with the calculated values obtained by ab initio, PM3 and MM+ methods, that can be used for docking of these stereochemical analogs onto α-estrogen receptors.     

Synthesis and properties of 8-phenylindolo-3,3′-trimethinecyanines

The condensation of 1-methyl-2-aryl-3-(2-benzoylvinyl)indoles with substituted indoles in acetic anhydride in the presence of a mineral acid afforded 8-phenylindolo-3,3-trimethinecyanines. Their spectral, polarographic, and photographic properties were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 499–501, April, 1992.     

Synthesis of ( ) 8-O-Cinnamyl-p-chlorogoniotriol and its Analogues

HowiinolAI',anovellactoneisolatedfromtheethanolicextractsoftherootandsternbarkofGoniolhanlush()TI)iiMerr.(Annoaceae)inourlaboratory.hasbeenshowntopossesssignificantantitullloractivitiestowardhumantumor117vilroandI,71'if'oandfoxytoxlcit}.Recently.wehavesynthesized1anditsderivativeswitllditTerentestergroupsstartingfromcommerciallyavailablea-D-glucoheptonic-y-lactone.Inordertotindtheirrelationshipofstructureandactivityandtosearchfordrugswithmorepotentantitumoractivity.wehavesynthesized( )8-O-…     

A catalytic version of hypervalent aryl-λ3-iodane-induced Hofmann rearrangement of primary carboxamides: iodobenzene as an organocatalyst and m-chloroperbenzoic acid as a terminal oxidant

The first catalytic version of hypervalent aryl-λ(3)-iodane-induced Hofmann rearrangement of primary carboxamides, which probably involves in situ generation of a tetracoordinated bis(aqua)(hydroxy)phenyl-λ(3)-iodane complex as an active oxidant from a catalytic amount of iodobenzene by the reaction with m-chloroperbenzoic acid in the presence of HBF(4) in dichloromethane-water under mild conditions, was developed.     

Synthesis of novel optically pure quinolyl-β-amino alcohol derivatives from 2-amino thiophenol and chiral α-acetylenic ketones and their IBX-mediated oxidative cleavage to N-Boc quinolyl carboxamides

A methodology directed toward the stereoselective synthesis of novel quinolyl glycines is presented. This strategy is based on the cyclocondensation reaction between 2-amino thiophenol 4 and chiral acetylenic ketones of the type 3 containing a latent α-amino acid functionality. The initially formed benzo[b][1,4]thiazepine derivatives 5, readily undergo sulphur extrusion in refluxing toluene to yield the corresponding 2,4-disubstituted quinolines 6. Subsequent oxazolidine ring opening followed by in situ re-protection of the amino group afforded the corresponding quinolyl-β-amino alcohols 8a–8f in enantiomerically pure form and good overall yields. The derivatives 8 are in principle suitable precursors for the synthesis of novel optically pure quinolyl glycines through oxidation of the alcohol side chain. However, these amino alcohol derivatives 8, did not afford the expected quinolyl glycines 10 using numerous oxidising agents and reaction conditions. Instead, by reacting 8 with the mild oxidising reagent IBX 11, an oxidative CC cleavage leading to the N-Boc quinolyl carboxamides 12 took place.     

Synthesis and biological evaluation of 4,5,6,7-tetrahydrothieno[2,3-c]pyridine–based β-aminonitriles and their derivatives: β-amino carboxamides, (thio)ureas,and tetracycles

The preparation and cytotoxic characterization of 4,5,6,7-tetrahydrothieno[2,3-c]pyridine–based β-aminonitriles, β-amino carboxamides, and their (thio)urea and annulated derivatives were accomplished. Following a synthetic route involving Gewald three-component reactions (G-3CR) and a Lewis acid–catalyzed iso (thio)cyanate coupling, 30 compounds were prepared for antitumor evaluation. For derivatizations, a catalytic amount of CuOAc₂ (20 mol%) was essential for improving the reactivity of either the C-2 amino function of thiophene or isocyanates. The synthesized analogues demonstrated a weak to moderate antitumor activity in a low micromolar range against A549 and K562 cancer cell lines.     

The Synthesis and Activity in vitro of a Series of 5-Amino-8-methoxyquinolones

A series of 1-cyclopropyl-5-amino-6-fluoro-8-methoxyquinoline-3-carboxylic acids have been prepared and evaluated for antibacterial activity in vitro.     

Optical response of bimetallic Li x Na8−x (0≦x≦8) and of doped Na8Zn clusters

Total (elastic + inelastic) cross-sections for electron scattering from C, N, O atoms and their simple molecules are studied theoretically. Thee ^–-C, N, O atomic calculations are done in the complex optical potential approach. To study the electron scattering from O₂, N₂, CO, NO, CN, C₂ as well as CO₂, N₂O, NO₂ O₃ targets, we have adopted an additivity rule, wherein the molecular cross-section is an incoherent sum of the cross-sections of the constituent atoms. The cross-sections of C, N & O atoms are presented at incident energiesE _i =10–1000 eV, the molecular cross-sections are presented atE _i =100–1000 eV. The reliability of the additivity rule is discussed against the background of experimental data.     

Synthesis and Amphiphilic Characteristics of 8－Hydroxyquinoline with Alkyl Chain

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Synthesis and properties of dithioacetals of conformationally constrainedα-acyl-β-aminovinyl ketones of the 8-azasteroid

We have the reaction of -acyl--aminovinyl of the 8-azasteroid series with ethanedithiol. The occurrence and orientation of the reaction are determined by structural and steric factors. As applied to derivatives of 8-azasteroids of the D-homo series, the reaction is irreversible and consequently the dithioacetal derivatives of this series are easily hydrolysed under acid and base conditions. Desulfurization over Raney nickel of the 17-dithioacetal derivative of 8-azagona-12,17-dione occirs with simultaneous dehydrogenation of the C ring and leads to the 17-deoxo-9,11-dehydro, ehile desulfurization of the 1-dithioacetal of 8-aza-D-homogona-12,17-a-dione leads to the 12-deoxo derivative. By reaction of the 12-dithioacetal of 8-aza-D-homogona-17a-one with hydroxylamine, we obtained the 12-oximino derivative, which is the result of an unusual reaction at the site of the spiro coupling of the dithiolane ring with the 8-azasteroid ring.Institute of Bioorganic Chemistry, Academy of Sciences of Belarus, Minsk, 220141. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 187–194, February, 1995. Original article submitted December 15, 1994.     

The synthesis and activity in vitro of a series of 8-difluoromethoxy quinolones： Analogues of gemifloxacin

7-[4-(Aminomethyl)-3-(methoxyimino)pyrrolidin-1-yl]-1-cyclopropyl-6-fluoro-8-difluoromethoxy-1,4-dihydro-4-oxoquino- line-3-carboxylic acid and its analogues have been prepared and evaluated for antibacterial activity in vitro.     

Study of Structures and Electronic Properties of Pdn–1Pb and Pdn （n≤8） Clusters

Geometric and electronic properties of Pdn–1Pb and Pdn (n≤8) clusters have been studied by using density functional theory with effective core potentials, focusing on the differences between mono- and bimetallic clusters. The average bond length of Pdn–1Pb (n≤8) bimetallic clusters is longer than that of pure palladium clusters except for n = 2 and 3. The most stable structure of Pdn–1Pb (n≤7) is the singlet where there is at least a Pd or Pb atom on its excited state. The energy gaps of Pd–Pb binary clusters are narrower than those of Pdn clusters, and then the chemical activity is strengthened when Pdn clusters are doped with Pb.     

Synthesis of the Analogs of Triptolide： 7, 8-Deoxytriptolide, 7 α, 8α-Epoxytriptolide and Related Ketones

Two novel analogues of triptolide were synthesized using triptolide as the starting material through reductive opening of epoxy ring, hydration and olefin epoxidation, and related ketones have also been afforded by oxidation of them with IBX or Jone‘s reagent.     

Synthesis and crystal structure of α-Ba2ZrF8 and Pb2ZrF8 determined ab initio from synchrotron and neutron powder diffraction data

α-Ba₂ZrF₈ is prepared as systematically twinned crystals by hydrothermal synthesis (200°C) or as fine powders either on a sand bath (60°C) (aqueous HF medium) or by solid state reaction at 450°C. Synchrotron radiation was used because of ambiguities in indexations from conventional X-ray (pseudo-hexagonal symmetry). The structure was determined ab initio from synchrotron powder data. Neutron data were used for improving accuracy because some degree of non-stoichiometry was suspected. The cell is orthorhombic, space group Prima, Z = 4, with a = 9.7401(1) Å, b = 5.6147(1) Å and c = 11.8871(1) Å (synchrotron data, 25°C). The final neutron Rietveld refinement led to R_P = 8.4 % and R_B = 3.5 % for the stoichiometric Ba₂ZrF₈ formulation (sand bath sample). The structure is built up from [ZrF₈] bicapped trigonal prisms isolated in a kinked fluorite matrix. The isostructural Pb₂ZrF₈ compound prepared in solution is also examined. An unexpected relationship with NaBaZrF₇ is discussed.     

Synthesis of 8-Methoxycarbonyloctylβ-Glycosides of Tri-and Tetrasaccharides Related to Schizophyllan and Neoglycoproteins Therefrom

Abstract

The 8-methoxycarbonyloctyl β-glycosides of the trisaccharides O-β-d-Glcp-(1 → 6)- O-β-d-Glcp-(1 → 3)-d-Glcp and O-β-d-Glcp-(1 → 3)-O-[β-d -Glcp-(1 → 6)]-d-Glcp and of the tetrasaccharide O-β-d-Glcp-(1 → 3)-O-[β-d-Glcp-(1 → 6)]-O-β-d-Glcp-(1 → 3)-d-Glcp, corresponding to the fragments of schizophyllan, have been synthesized by using mono- to tetrasaccharide 1-thioglycosides as glycosyl donors, each bearing a participating benzoyl group in the 2-position, and N-iodosuccinimide and silver triflate as promoter. Saponification of the tri- and tetrasaccharide β-glycosides, followed by attachment to bovine serum albumin of the resulting sugar derivatives having a carboxyl group at the aglycon terminal, provided neoglycoproteins for immunological studies of the polysaccharide.     

Preparation and Characterization of TiO2-pillared Layered HNb3O8

IntroductionThelayeredcompoundssuchassmectiteclays,me-tallicphosphatesandtransitionmetaloxidespillaredwithinorganicoxideshavebeenattractingmoreandmoreattentionfrombothacademicandindustrialfieldsduetotheirpotentialapplicationsinadsorption,separa-tion,conductionandparticularlycatalysis.1-7NiobatessuchasKNb3O8andK4Nb6O17,andthecorrespondingprotonicoxides,HNb3O8andH4Nb6O17,aremembersofthefamilyoflayeredtransitionmetaloxidesbasedonoctahedralframeworkstructure,inwhichK+orH+liesbetweenlayersbuil…