bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intercalates With Linear Polymer Host. Part V. Optical Determination of the orientation of the guest molecules in [(CH2CH2O‐)10 (C6H4Cl2)3]n intercalates
Authors: Point J. J. , Coutelier Cl. 
Published: September 2010

AbstractThe orientation of pC6H4Cl2 in the [(pC6H4Cl2)3 (CH2CH2O)10]n crystalline intercalate previously studied by X‐Ray diffraction and FTIR spectroscopy, is obtained by measurement of birefringence of fibres of this compound.
Synthesis and Identification of Vicinal Azaoxo‐2(3)‐Homodiamantanes
Authors: Tinant B. , Declercq J. P. , van Meerssche M. , Janko J. , Burkhard J. , Hajek M. , Vodiĉka L. 
Published: September 2010

AbstractThe Schmidt reaction of diamantanone has been studied in details. The main products of the reaction were separated by means of the elution chromatography on silica gel. Obtained compounds 10‐aza‐11‐oxohomodiamantane (VI) and 11‐aza‐10‐oxohomodiamantane (IX) were analysed by X‐ray diffraction. These compounds as well as 5ax‐hydroxy‐and 5eq‐hydroxy‐3‐diamantanones were also analysed by using 13C NMR additive rules.
4,5‐Diphenylimidazoles from the Cyclization of Benzil N‐Alkylmonohydrazones
Authors: Collibee† William L. , Anselme Jean‐Pierre 
Published: September 2010

AbstractThe thermal cyclization of monodisubstituted hydrazones (1) affords the corresponding N‐substituted‐4,5‐diphenylimidazoles in good to excellent yields; possible mechanisms for this unusual cyclization are presented.
Citricolic Acid, a Novel Type of Fungal Metabolite
Authors: Ayer William A. , Dufresne Claude 
Published: September 2010

AbstractCitricolic acid, a metabolite of the fungus Mycena citricolor, has been shown to possess structure 1. The structure was elucidated by a combination of physical and Chemical methods. Citricolic acid (1) is a new type of natural product which appears to be a degraded steroid. A possible biogenesis of 1 is discussed.
Sesquiterpenes with New Carbon Skeletons, Furoeremophilanes, Secoeremophilanes and other Constituents from Argentinian Senecio Species
Authors: Bohlmann F. , Jakupovic J. , Warning U. , Grenz M. , Chau‐Thi T. V. , King R. M. , Robinson H. 
Published: September 2010

AbstractThe investigation of ten further Senecio species afforded 24 new furanoeremophilanes, 18 eremophilanolides, seven seco‐ and two rearranged eremophilanolides, twelve bisabolone derivatives and six sesquiterpenes with new carbon skeletons which are most likely derived from the latter. Possible biogenetic pathways are discussed. Furthermore five new eremophilones, an eudesmane, four p‐hydroxyacetophenone, a bis‐coniferylalcohol derivative and five shikimic acid derivatives were isolated. The structures were elucidated by using highfield NMR techniques and other spectroscopic methods.
Sarains: A New Class of Alkaloids from the Marine Sponge Reniera Sarai
Authors: Cimino Guido , Stefano Salvatore De , Scognamiglio Gennaro , Sodano Guido , Trivellone Enrico 
Published: September 2010

AbstractReniera sarai, a marine sponge of the Ceractinomorpha subclass easily collectable in the Bay of Naples, is characterized by a series of cyclic nitrogenous compounds, which for many years have resisted all attempts of structural investigation.Complex separation steps have now led to three new compounds, named sarain‐1, sarain‐2 and sarain‐3. Their structures have been partially determined mainly by a 500 MHz NMR study, utilizing the 1H‐1H homonuclear and 1H‐13c heteronuclear NMR Chemical shift correlation techniques. Sarains belong to a new class of pentacyclic alkaloids, containing in their skeletons a quinolizidine system linked to a tetrahydropyridine moiety. Two linear alkyl chains, placed between the two heterocyclic systems, supply the two remaining cycles. Recently a series of biologically active bis‐quinolizidine and 1‐oxa‐quinolizidine alkaloids have been isolated from the sponges Petrosia seriata and Xestospongia exigua, respectively. A common biogenetic origin should connect these alkaloids to sarains. Sarains show phase transfer catalytic properties.
Carotenoids of the Sponge Polymastia Granulosa (Hadromerida)
Authors: Hertzberg Sissel , Englert Gerhard , Bergquist Patricia , Liaaen‐Jensen Synnøve 
Published: September 2010

AbstractThe background information on natural carotenoids (new aspects), NMR spectroscopy of carotenoids (present status) and sponge chemosystematics, relevant to the present study, is briefly reviewed.The quantitative carotenoid composition of Polymastia granulosa has been determined by methods including TLC, HPLC, VIS, 1H NMR and MS.Isorenieracistene (7‐cis‐φ,φ‐carotene) was the major carotenoid, further characterized by 2D 1H NMR (400 MHz), and isomerization studies. Its stability is discussed.The 1 H NMR spectrum of 7,9'‐dicis isorenieratene, a likely isolation artifact, was fully assigned by 1D Double Indor Difference experiments and 2D 1H NMR.All three reports on Δ‐cis aryl carotenes concern sponges of the order Hadromerida. Possible cis hydrogenation of algal carotenoid precursors is considered.
Starfish Saponins XXX. Isolation of Sixteen Steroidal Glycosides and Three Polyhydroxysteroids from the Mediterranean Starfish Coscinasterias Tenuispina
Authors: Riccio Raffaele , Iorizzi Maria , Minale Luigi 
Published: September 2010

AbstractSixteen steroidal glycosides have been isolated from the starfish Coscinasterias tenuispina. The more polar components are the “asterosaponins” 1A–1E, 2A–2C, 3E and 3G, consisting of a Δ9(11)‐3β,6α‐dihydroxysteroidal moiety, a pentasaccharide portion attached at C‐6 and a sulphate group at C‐3. Compounds 1C, 2C and 1D are new saponins assigned as the tenuispinoside A through C. The second group of polar glycosides consists of two new xylose saponins, possessing monosulphate polyhydroxysteroidal aglycones and two new 4‐O‐sulphated glucose saponins, assigned as the coscinasteroside A through D (4–2). The less polar glycosides are the new “non‐sulphated” xylosides 8 and 9, designed as coscinasterosides E and F.The structures of the new saponins were determined by extensive 1H and 13C NMR investigations, FAB mass spectroscopy, and by comparison with known compounds. The location of the sulphate ester functionalities in 4–7 were assigned on comparison of their spectral data with those of the corresponding desulphated analogues. C. tenuispina also contains three new monosulphated polyhydroxysteroids, which were assigned the structures 10 to 12.
Synthesis of Radiolabeled Juvenile Hormone Analogs and Chiral Homologs
Authors: Eng Wai‐Si , Prestwich Glenn D. 
Published: September 2010

AbstractRadiolabeled juvenile hormone (JHs) and labeled JH derivatives are required for the study of JH metabolism and JH‐protein interactions as well as JH radioimmunoassay in insects. The progress in the synthesis of these labeled compounds for the last five years is reviewed, including the preparation of photoaffinity labels, enantiomerically enriched JH I and JH II with 3H labels, and radioiodinated analogs of JH I, methoprene and phenoxyphenyl ether insect growth regulators (IGRs). Experimental details are given for the efficient synthesis of two 3H‐labeled photoactivatable JH analogs, EFDA and EFTP, their photolysis in methanol, and their competitive binding assays performed on the Manduca sexta JH binding proteins (JHBP).
Novel Heterocycles by the Malonic Ester Variation of the Japp‐Klingemann Reaction
Authors: Heckendorn Roland 
Published: September 2010

AbstractAzocompounds prepared by coupling malonic ester derivatives with diazotized anilines, 3‐amino‐2‐chloropyridine, anthranilic ester or 2‐aminobenzophenones are shown to be versatile intermediates for the synthesis of various polyaza‐heterocycles.
XIIth European Colloquium on Heterocyclic Chemistry “Phosphorus azides, powerful reagents in heterocyclic chemistry”
Authors: Majoral Jean‐Pierre , Bertrand Guy , Ocando‐Mavarez Edgar , Baceiredo Antoine 
Published: September 2010

AbstractThe Curtius type rearrangement is effective for tetracoordinated and pentacoordinated phosphorus azides. Competitive nitrene‐type reactions sometimes occur. On the other hand, irradiation of tricoordinated phosphorus azides lead to the generation of phosphorus nitrogen triple‐bonded species. The photolysis or the thermolysis of all these derivatives appears to be a convenient route for the synthesis of new heterocyclic compounds.
Biomimetic Oxidation of Hydrocarbons and Drugs by Metalloporphyrinic Systems
Authors: Mansuy D. , Battioni P. 
Published: September 2010

AbstractMost biological oxidations of exogenous compounds, such as drugs and endogenous compounds, especially when the hydroxylation of an inert C‐H bond is involved, are catalyzed by cytochrome P‐450‐dependent monooxygenases. These enzymes have the unique ability to transfer an oxygen atom from oxygen atom donors including O2 into almost any organic substrates including alkanes in a highly selective manner. Based on the knowledge of the mechanisms of substrate oxidation by these cytochromes, chemical model systems using metalloporphyrin catalysts have been built. In particular, a very efficient system for hydrocarbon oxidation by H2O2 in mild conditions is described. It is also shown that Fe‐ and Mn‐porphyrins catalyze the transfer of the NR nitrene moiety of PhI=NR compounds into hydrocarbons leading to direct aziridination of alkenes and amidation of alkanes with high yields.
Applications of N‐Sulfinyl Dienophile Diels‐Alder Cycloadditions to Synthesis of Unusual Amino Sugars
Authors: Weinreb Steven M. , Gainor James A. , Joyce Richard P. 
Published: September 2010

AbstractThe amino sugar moieties of staurosporine and nogalarol have been stereospecifically synthesized by a strategy utilizing N‐sulfinyl Diels‐Alder chemistry.
Intermolecular Charge‐Transfer Complexes of Arylthiourea Derivatives
Authors: Nour El‐Din Ahmed M. 
Published: September 2010

AbstractIntermolecular charge‐transfer complexes between arylthiourea derivatives and tetracyanoethylene in methylene chloride at 25°C have been studied spectro‐photometrically in the visible region. The spectral data indicate that the complexes are weak and the Ph‐N‐CS‐N moiety is responsible for complexation with tetracyanoethylene. Job's method shows that the stoichiometric ratio of the complexes is 1:1. The ionization potentials of the donors were calculated from the energy of charge transfer transitions.
Adsorption of Malathion on Activated Sepiolite from Cyclohexane Solution
Authors: González‐Pradas E. , Villafranca‐Sánchez M. , Plaza‐Capel R. J. , Del Rey‐Bueno F. 
Published: September 2010

AbstractAdsorption of malathion on four natural sepiolite samples activated by different combined acid and heat treatments (0.25 N and 0.5 N, HNO3; 110°C and 200°C) from cyclohexane, has been studied. The adsorption isotherms may be classified as H‐3 type of the Giles classification which suggests that malathion molecules are strongly adsorbed on the sepiolite samples and that there is no competition from solvent for adsorption sites. The experimental data points have been fitted to the modified B.E.T. equation in order to know the adsorptive capacities (Xm) of the solids as well as their surface areas (S) available to the malathion molecules.Xm values range from 1.35x10−1 molxKg−1 up to 2.47x10−1 molxKg−1, the maximum values corresponding to the sample activated with 0.5 N HNO3 solution and treated at 110°C. S values range from 70x103 m2xKg−1 up to 128x103 m2xKg−1, the maximum values also corresponding to the sample activated with 0.5 N HNO3 solution and treated at 110°C.
Modulation de la Régiosélectivité Lors de la Cycloaddition de la Diphénylnitrilimine Sur Divers Dihydro‐1,2 Naphtalènes Substitues, Stéréospecificité de la Réaction
Authors: Tshiamala Kabula , Kitane Saïd , Vebrel Joël , Laude Bernard 
Published: September 2010

AbstractIn order to control the regiochemistry of the cycloaddition of diphenylnitrilimine on 1,2‐dihydronaphtalene and at‐1 or −2 substitued derivatives and to obtain either regioisomer, we introduce a methoxycarbonyl group at the 4− or 3− position of the dipolarophile. The reactions are thus highly regioselective or specific.Moreover each reaction is stereospecific and the approach of the dipole occurs from the less hindered diastereotopic side of the dipolarophile.
Étude Par Spectrométrie de Masse en Tandem D'Ions [C6H12O]+. Isomères
Authors: Beynon J. H. , Flammang R. , Kingston E. E. , Maquestiau A. 
Published: September 2010

AbstractIon kinetic energy spectrometry using two triple sector instruments has been used for the study of the fragmentation of ionized 5‐nonanone. Mixtures of isomeric [C6H12O]+. ions are formed in the first McLafferty rearrangement whose relative proportions depend on their internal energy.
Redox Potentials of Mixtures of Aldrithiol‐2 with 2‐Mercaptopyridine
Authors: Antelo J. M. , Arce F. , Sastre M. , Varela A. 
Published: September 2010

AbstractThe redox characteristics of mixtures of aldrithiol‐2 with 2‐mercaptopyridine have been studied in the range pH 0.3‐8.4 using a platinum electrode. Reversible two‐electron reactions were observed. In these mixtures the graphs of “formal potential” against pH depend on the various acid‐base equilibria present. The results show that for a given value of pH the “formal potential” measured is more positive than that determined polarographically using a dropping mercury electrode.
Molecular Structures of the Internal Acetals Derived from (1S, 10S)‐ and (1R, 10R) ‐ Dihydroxy‐3β‐Acetoxy‐5, 10‐Seco‐5‐Cholestanones
Authors: Tinant B. , Declercq J. P. , van Meerssche M. , Lorenc Lj. , Mihailovic M. Lj. 
Published: September 2010

AbstractThe molecular structures of the acetals 3b and 5a, obtained from (Z) ‐ 38‐ acetoxy‐5, 10‐seco‐cholest‐1 (10)‐en‐5‐one (1) via the cis‐(1S, 10R)‐epoxide 2, and from (E)‐3β‐acetoxy‐5, 10‐seco‐cholest‐1 (10)‐en‐5‐One (4) via the corresponding (1S, 10S)‐ and (1R, 10R)‐osmate esters, have been determined by X‐ray analysis.
Synthesis of Carbomethoxydiphenyl Sulfones, Mass and Proton‐NMR Spectral Studies
Authors: Briñón M. C. , De Bertorello M. M. , Bertorello H. E. , Luna L. 
Published: September 2010

AbstractFour carbomethoxydiphenyl sulfone compounds are formed in the reaction of 4,4′‐dibromo (I) and 4,4′‐diiododiphenyl sulfone (II) with n‐butyllithium in tetrahydrofuran at ‐60°C. Their mass and proton‐nuclear megnetic resonance spectra are discussed.
Le 1,2,2‐Trichloronitrosoéthylène Comme Dienophile ou Hétérodiene en Cycloadoition de Diels‐Alder
Authors: Ascherl B. , Kresze G. , Vaerman J. L. , Vandenbulcke‐Coyette B. , Viehe H. G. 
Published: September 2010

Abstract1,2,2‐trichloronitrosoethylene reacts either as dienophile or as a heterodiene depending on the nature of its partners in the Diels‐Alder reaction.
Synthèse et Hererocyclisation des (Pyrazolyl‐3(5))‐2 Benzimidazoles en Catalyse Par Transfert de Phase
Authors: Essassi E. M. , Fifani J. 
Published: September 2010

AbstractFusion of o‐diamines with pyrazolylhydrazides 2a‐2b gives the new 2‐pyrazolylbenzimidazoles 3a‐3l. The application of phase transfer catalysis to the N‐alkylation of compounds 3a‐3d leads to pyrazines 4a‐4d and diazépines 5a‐5d.
Deoxygenation of Cresol on Houdry and Modified Houdry Catalysts
Authors: Jachintha M. A. , Rajadurai S. 
Published: September 2010

AbstractPhysico chemical characterization of the Houdry catalyst supplied by the Houdry corporation, New Jersey shows that it is an amorphous form of silica alumina containing traces of calcium and potassium. It is modified by heat treatment and by loading strong metal oxides such as MoO3 and NiO. The catalytic activity for the deoxygenation of o− cresol on these systems were studied at 623 K. Very high percentage conversion (90%) was obtained on Houdry catalyst. However the conversion is not significantly altered by heat treatment of the catalyst in the temperature range 623 K to 723 K. The incorporation of the MoO3 in the catalyst enhances the activity. The MoO3‐NiO impregnation further increases the percentage conversion of cresol. The increase in percentage conversion on these strong metal supported catalysts may be due to the addition of the multivalent metallic active sites for the cresol to be adsorbed on the surface through oxygen coordination.
Sedum Alkaloids. IX1. Isolation from sedum acre and x‐ray structure determination of lobelanidine glycoside
Authors: Piccinni‐Leopardi C. , Tinant B. , Declercq J. P. , van Meerssche M. , Hootelé C. 
Published: September 2010

AbstractLobelanidine occurs in Sedum acre as the glycoside 1 whose complete structure has been established by spectroscopic and X‐ray diffraction methods.
Intramolecular Diels‐Alder Reaction with Furan‐Diene. Activated Allene as Dienophile in a BCD‐ring Approach to Steroids
Authors: Missisen Patrick , De Clercq Pierre J. 
Published: September 2010

AbstractIn connection with the total synthesis of corticosteroids and some triterpenoids the intramolecular Diels‐Alder reaction of furans 7 and 9, possessing an activated allene as dienophilic side chain, is investigated, and compared with the cycloaddition of the analogous α, β‐unsaturated enone 5. Differences in stereoselectivity are ascribed to the enhanced exothermicity of allene dienophiles. Observed reactivity differences and the stereochemical outcome are rationalized on the basis of an asynchronous reaction course. Most important, the allene dienophile allows for carbon elongation in β ‐position of the dienophile 5 without loss of reactivity in the cycloaddition.
A Simple Preparation of Cyanosilanes from the Corresponding Chloroderivatives by Transcyanogenation
Authors: Becu Chr. , Anteunis M. J. O. 
Published: September 2010

AbstractQuantitative yields of pure cyanosilanes are obtained from the corresponding chlorides by transcyanogenation with cyanotrimethylsilane under catalysis of a small amount KF. This is the most direct method with minimum handling in order to obtain these moisture‐sensitive derivatives.
Trimethylsilyl Cyanide in Peptide Strategies. Part III. Needlessness for complementary hydroxyl side‐chain protection
Authors: Anteunis M. J. O. , Becu Chr. , Becu F. , Callens R. 
Published: September 2010

AbstractNo extra side‐chain protection is needed for Ser, Thr, Tyr and Cys (nor for Asp and Glu) in peptide syntheses that are mediated by TMS‐CN, whereby silylesters and ethers are formed and are stable enough even during activation of carboxylic components. This allows Head‐to‐Tail elongation strategies and fragment condensations without recourse to additional side‐chain protection except for amine and amide functionalities. Moreover, stereomutation during the H‐t‐T preparation of Z‐Trp‐ Ser‐Tyr‐OH and Z‐Ser‐Tyr‐Gly‐OH is almost absent.
The Dynamics of Biomineral Systems
Authors: Driessens F. C. M. , Borggreven J. M. P. M. , Verbeeck R. M. H. 
Published: September 2010

AbstractEvidence accumulates that mineralization in the body, whether physiological or pathological, takes place only, when and where body fluids become supersaturated with respect to the formation product of fast nucleators like brushite, octocalcium phosphate, calcite and calcium oxalates. In the pH ranges above 8.0, between 8.0 and 7.0 and below 7.0 the most frequently occurring nucleating phases are calcite, octocalcium phosphate and brushite, respectively.After nucleation of brushite this phase is transformed spontaneously into a mixture of a sodium‐ and carbonate containing apatite, of dolomite and of calcium deficient hydroxyapatite. After nucleation of octocalcium phosphate that phase is transformed spontaneously into a mixture of a sodium‐ and carbonate containing apatite, of magnesium whitlockite and of heavily carbonated calcium deficient hydroxyapatite. In addition, other phases can be formed in the presence of enough fluoride, zinc, etc.
Attempted Synthesis of the Dithiophene Analogs of Biphenylene
Authors: Párkányl Cyril , Huang Deeng‐Lih , Kalsotra Bansi L. , Jeffries Alfred T. , Lloyd Winston D. 
Published: September 2010

AbstractSynthesis of the four possible dithiophene analogs of biphenylene (1), viz., cyclobuta[1,2‐b:3,4‐d′]dithiophene (3), cyclobuta[1,2,‐b:3,4‐b′]‐dithiophene (4), cyclobuta[1,2‐b:3,4‐c′]dithiophene (5), and cyclobuta‐[1,2‐c:3,4‐c′]dithiophene (6) has been explored using several different approaches. All these attempts have been unsuccessful similarly as the former efforts of Mc Omie and Wynberg. Equally unsuccessful were the attempts to obtain the iron tricarbonyl complexes of these compounds which were thought to be more stable. The HMO calculations carried out for cyclobutadithiophenes indicate that these four compounds will be highly unstable, also in view of the considerable ring strain.
Crystal Structure and Conformation of Short Linear Peptides: Part I: L‐Phenylalanyl‐Glycyl‐Glycine
Authors: Wu S. , Tinant B. , Declercq J. P. , van Meerssche M. 
Published: September 2010

AbstractC13H17N3O4, Mr = 279.30, orthorhombic, P212121, a = 5.743(2), b = 16.072(10), c = 15.317(10)Å, V = 1347(1)Å3, Z = 4, Dx = 1.38 g. cm−3, MoKα, λ = 0.71069 Å, μ = 1.12 cm−1, F(000) = 592, T = 291K, R = 0.036 for 1372 observed reflections. The molecule partly assumes a 310‐helical conformation. The side chain of the Phe residue has an unusual conformation characterized by angles X1 = 176° and X21 = 53°.
Ba(OH)2 as the Catalyst in Organic Reactions‐Part X‐Reaction of Chalcone with Hydroxylamine
Authors: Sinisterra J. V. , Marinas J. M. 
Published: September 2010

AbstractThe reaction of several chalcones with hydroxilamine has been studied. A systematic catalytic study of the synthetic process has been accomplished. The different experimental conditions have been studied. The process catalyzed in the homogeneous phase gives mixture of products. Nevertheless the process catalyzed by activated barium hydroxide catalyst, C‐200., in heterogeneous phase, produces Δ2 ‐isoxazolines with high yields and selectivities. The ‐ mechanism of the process in the heterogeneous phase is discussed. The poisoning effect on the C‐200 active sites, produced by an excess of NH2OH is analyzed. Some reactions products are described by the first time.
Synthesis of 7,8‐Didehydro‐3,4‐Dimethoxy‐17‐Methylmorphinan‐6‐one and the Regioselective Reduction of the Keto Function (Chemistry of Opium Alkaloids, Part XXIV)
Authors: van Gurp R. A. , Lie T. S. , Mense C. , Maat L. 
Published: September 2010

Abstract7,8‐Didehydro‐3,4‐dimethoxy‐17‐methylmorphinan‐6‐one (2) was prepared by reductive opening of the epoxy bridge of codeinone, followed by methylation with Rodionow's reagent. Reduction of the title compound with sodium tetrahydroborate in the presence of cerium(III) chloride afforded a mixture of 7,8‐didehydro‐3,4‐dimethoxy‐17‐methylmorphinan‐6α‐ol (3) and ‐6β‐ol (4) in a ratio of 4:1 from which the 6α‐epimer was crystallized and converted into the acetate (7).
Crystal Structure and Conformation of Short Linear Peptides Part II: L‐Tryptophanyl‐Glycyl‐Glycine Dihydrate
Authors: Wu S. , Tinant B. , Declercq J. P. , van Meerssche M. 
Published: September 2010

AbstractC15H1N4O4, 2H2O, Mr = 354.41, orthorhombic, P21 21 21, a = 9.019(8), b = 7.909 (3) c = 24.336(23) Å, Z = 4, Dx = 1.36 gcm−3, MoKα, λ = 0.71069 Å, μ = 1.14 cm−1, F(000) = 752, T = 291K, R = 0.061 for 1014 observed reflections. The molecule adopts a conformation somewhat similar to a segment of a lefthanded α‐helix. The side chain of the Trp residue takes an usual conformation described by χ1 = ‐172° and χ21 = ‐79°.
Syntheses and Spectral Characterization of the Metabolites of a New Organo‐Selenium Drug: Ebselen
Authors: Lambert C. , Cantineau R. , Christiaens L. , Biedermann J. , Dereu N. 
Published: September 2010

AbstractThe syntheses and spectral characterization of the metabolites of a new organo‐selenium drug (ebselen) are described.