ZIB

1

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On kaonic deuterium. Quantum field-theoretic and relativistic covariant approach (2005)

Ivanov, A. N. ; Cargnelli, M. ; Faber, M. ; [et al.]

Springer

The European physical journal 23 (2005), S. 79-111

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ISSN: 1434-601X

Keywords: 11.10.Ef Lagrangian and Hamiltonian approach ; 11.55.Ds Exact S matrices ; 13.75.Gx Pion-baryon interactions ; 36.10.-k Exotic atoms and molecules (containing mesons, muons, and other unusual particles)

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract. We study kaonic deuterium, the bound K-d state AK d. Within a quantum field-theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic deuterium in terms of the amplitude of K-d scattering for arbitrary relative momenta. Near threshold our formula reduces to the well-known DGBT formula. The S-wave amplitude of K-d scattering near threshold is defined by the resonances Λ(1405), Σ(1750) and a smooth elastic background, and the inelastic channels K-d → NY and K-d → NYπ, where Y = Σ±,Σ{0} and Λ{0}, where the final-state interactions play an important role. The Ericson-Weise formula for the S-wave scattering length of K-d scattering is derived. The total width of the energy level of the ground state of kaonic deuterium is estimated using the theoretical predictions of the partial widths of the two-body decays AKd → NY and experimental data on the rates of the NY pair production in the reactions K-d → NY. We obtain Γ{1s} = (630±100)eV. For the shift of the energy level of the ground state of kaonic deuterium we predict ε{1s} = (325±60)eV.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1140/epja/i2004-10055-3

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2

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From solar proton burning to pionic deuterium through the Nambu-Jona-Lasinio model of light nuclei (2005)

Ivanov, A. N. ; Cargnelli, M. ; Faber, M. ; [et al.]

Springer

The European physical journal 23 (2005), S. 1-6

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ISSN: 1434-601X

Keywords: 11.10.Ef Lagrangian and Hamiltonian approach ; 13.75.Gx Pion-baryon interactions ; 36.10.-k Exotic atoms and molecules (containing mesons, muons, and other unusual particles) ; 26.65.+t Solar neutrinos

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract. Within the Nuclear Nambu-Jona-Lasinio model of light nuclei (the NNJL model), describing strong low-energy nuclear interactions, we compute the width of the energy level of the ground state of pionic deuterium. The theoretical value fits well the experimental data. Using the cross-sections for the reactions νe + d → p + p + e- and νe + d → p + n + νe, computed in the NNJL model, and the experimental values of the events of these reactions, detected by the SNO Collaboration, we compute the boron neutrino fluxes. The theoretical values agree well with the experimental data and the theoretical predictions within the Standard Solar Model by Bahcall. We argue the applicability of the constraints on the astrophysical factor for the solar proton burning, imposed by helioseismology, to the width of the energy level of the ground state of pionic deuterium. We show that the experimental data on the width satisfy these constraints. This testifies an indirect measurement of the recommended value of the astrophysical factor for the solar proton burning in terrestrial laboratories in terms of the width of the energy level of the ground state of pionic deuterium.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1140/epja/i2004-10070-4

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3

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Steroid biochemistry of virilising adrenal tumours in childhood (1984)

Honour, J. W. ; Price, D. A. ; Taylor, N. F. ; [et al.]

Springer

European journal of pediatrics 142 (1984), S. 165-169

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ISSN: 1432-1076

Keywords: Adrenal gland neoplasms ; Urine steroids ; Gas chromatography ; Mass spectrometry

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract Steroid excretion in urine of 12 infants with virilising adrenal tumours has been determined using gas chromatography. In six children, (Group A, five female, one male) aged 2.8–5.3 years, very high urinary excretions of 17 oxosteroids (〉40 μmol/24 h) were largely accounted for by dehydroepiandrosterone (DHA). In one of the girls, the pattern of steroids excreted in urine was similar to that of newborn infants, with high excretions of 16-oxygenated derivatives of DHA. The histology of this tumour suggested a neoplasia of fetal-type adrenocortical cells. Very large tumours were found in three of the infants, two of whom have died and one has multiple metastases. From the other three children, small, well-encapsulated adenomas were successfully removed. Six children (Group B), had moderately elevated 17-oxosteroid exrretions (8–17 μmol/ 24 h). In five of these cases (four female, one male) aged 0.8–5 years, 11β-hydroxyandrosterone was a consistently prominent urinary steroid. In one boy, aged 7.7 years, 17-oxosteroid excretion was 15 μmol/24 h and the major steroids in urine were metabolites of pregnenolone. These six children have survived with no clinical evidence of recurrent tumour. The in vivo functional activities of the tumours can be deduced from the different profiles of steroids in urine. These have revealed heterogeneous patterns of steroid biosynthesis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00442442

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4

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Stereoselectivity of enzymes involved in toxicity and detoxification of soman (1984)

Nordgren, Ingrid ; Lundgren, Gösta ; Puu, Gertrud ; [et al.]

Springer

Archives of toxicology 55 (1984), S. 70-75

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ISSN: 1432-0738

Keywords: Soman ; Gas chromatography ; Mass spectrometry ; Cholinesterases ; Aliesterase ; Phosphorylphosphatase ; Toxicity ; Stereoselectivity

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract The fate of the four stereoisomers of soman [0-(1,2,2-trimethylpropyl)-methyl-fluoro phosphonate] has been studied a) in vivo in mouse blood and liver after IP injection of 0.75 × LD50 Rc- and Sc-soman respectively, and b) in vitro upon incubation wih acetyl- und pseudocholinesterase, aliesterase and phosphorylphosphatase. The analytical method used is based on gas chromatography — mass spectrometry with deuterated internal standard. Most soman disappeared very rapidly from blood and liver. In liver, SCRP and RCRP, the two isomers that preferentially react with cholinesterase, could be detected. The level of SCRP, which was higher than that of RCRP, could be followed for 17–18 h. In blood only SCRP could be detected. The amounts found were fairly constant during the time period 2 min to 4h, and it could even be detected 17–18 h after soman administration.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00316590

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5

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The determination of environmental 2-ethoxyethanol by gas chromatography (1984)

Sidhu, K. S.

Springer

Archives of toxicology 55 (1984), S. 272-275

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ISSN: 1432-0738

Keywords: 2-Ethoxyethanol ; Teratogen ; Adsorption ; Desorption ; Gas chromatography

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract A gas Chromatographic procedure for the determination of 2-ethoxyethanol (C2H5OCH2CH2OH) was developed by using the general principles of analysis of solvent vapors. 2-Ethoxyethanol was sampled by adsorbing on activated carbon. It was desorbed with carbon disulfide plus 2-propanol (0.5%). The analytical column was packed with 10% free fatty acid phase on Chromosorb-P AW. The analysis was conducted at 130° C isothermal using a flame ionization detector. Addition of 2-propanol (0.5%) to carbon disulfide improved (P≤0.01) desorption of 2-ethoxyethanol adsorbed on activated carbon. The mean desorption efficiency of carbon disulfide plus 2-propanol (0.5%) was 87.9±2.86% (n=15). Based on a 101 air sample and detector sensitivity of 2×10−10AFS, the calculated limit of detection of 2-ethoxyethanol was 0.1 ppm. The precision (coefficient of variation) for this analytical procedure was 3.34% (n=12). In conclusion, 2-ethoxyethanol adsorbed on activated carbon can be desorbed with carbon disulfide plus 2-propanol (0.5%). Subsequently the desorbed 2-ethoxyethanol can be analyzed by gas chromatographic identification on 10% FFAP using a flame ionization detector.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00341025

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6

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Determination of free fractions of tricyclic antidepressants (1984)

Nyberg, Gösta ; Mårtensson, Erik

Springer

Naunyn-Schmiedeberg's archives of pharmacology 327 (1984), S. 260-265

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ISSN: 1432-1912

Keywords: Amitriptyline ; Imipramine ; Clomipramine ; Demethylated metabolites ; Free fractions ; Serum ; Equilibrium dialysis ; Gas chromatography ; Binding parameters

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary The plasma protein binding of amitriptyline, imipramine, clomipramine, and their primary demethylated metabolites were studied by means of a method combining dialysis and gas chromatography. Equilibrium in dialysis of serum containing amitriptyline and its metabolite nortriptyline was attained in about 0.5 h with the drug dissolved in the serum compartment, and in about 2 h with the drug passing from the buffer to the serum compartment. The calculation of free fractions was influenced by variations with dialysis time in the volumes of serum and buffer. Increase of pH in serum increased the protein binding of the weakly basic drugs studied, and made the Donnan distribution effects more pronounced. At pH 7.4, the Donnan effect was negligible. Binding parameters for the 6 tricyclic antidepressant substances studied were estimated for the binding to α1-acid glycoprotein and for total binding in serum. For α1-acid glycoprotein, the k-values ranged from 1·105 to 8·105 M−1, and for pooled serum from 0.4·105 to 8·105 M−1. The determined number of binding sites on the α1-acid glycoprotein was, on average 0.87 for the 6 substances. In serum, the binding capacity was 2–14 times the concentration of α1-acid glycoprotein.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00502459

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7

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Esterification of C2−C16 dicarboxylic acids to n-butyl esters in aqueous solutions for their gas chromatographic analysis (1984)

Molnár-Perl, I. ; Fábián-Vonsik, V. ; Pintér-Szakács, M.

Springer

Chromatographia 18 (1984), S. 637-641

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ISSN: 1612-1112

Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of C2−C16 dicarboxylic acids ; Dicarboxylic acid analysis

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary C2−C16 dicarboxylic acids were esterified in aqueous solution in the presence of sulfuric acid. Esterification in water/n-butanol mixtures with mole ratios between 0.02 and 2.53 can be utilized for the quantitative determination of the dicarboxylic acids by gas chromatography. The presence of water does not interfere at water/n-butanol mole ratios below 0.27. For mole ratios above 0.27 anhydrous sodium sulfate has been used for binding the water. The mole ratio range was 0.25–0.75 for anhydrous sodium sulfate/water, and 0.32–1.3 for sulfuric acid/anhydrous sodium sulfate.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02261980

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8

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Solubilities and partial molar enthalpies of solution for polar gas-liquid systems determined by gas chromatography (1984)

Sweeney, C. W.

Springer

Chromatographia 18 (1984), S. 663-667

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ISSN: 1612-1112

Keywords: Gas chromatography ; Gas solubilities ; Enthalpies of solution ; Polar solutions

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary The gas-liquid chromatographic method has been used to determine the solubilities and partial molar enthalpies of solution of the gases H2S, CO2 and COS in four polar solvents. The results agree well with literature values obtained using conventional techniques, with the one exception of H2S in N-methyl-2-pyrrolidinone. In this case there is some evidence for the occurrence of adsorption at the gas-liquid interface.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02265810

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9

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Gas chromatographic analysis of aromatic, carboxylic acids in the presence of C1−C5 fatty acids and C2−C7 dicarboxylic acids esterified in aqueous solutions as the n-butyl esters (1984)

Molnár-Perl, I. ; Fábián-Vonsik, V. ; Pintér-Szakács, M.

Springer

Chromatographia 18 (1984), S. 673-676

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ISSN: 1612-1112

Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of aromatic polycarboxylic acids

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary The direct esterification and gas chromatographic analysis of aromatic carboxylic acids as n-butyl esters is described. Derivatization is performed in aqueous solution with n-butanol in the presence of sulfuric acid. The butyl esters of benzoic, phthalic, hemimellitic, trimellitic, trimesic and pyromellitic acids permit their gas chromatographic separation from each other and from fatty acids and alipatic dicarboxylic acids. At mole ratios of [H2O]/ [n-BuOH]≤0.04 the water present does not interfere with the esterification reaction. At mole ratios above 0.04 anhydrous sodium sulfate is used for binding the water, at mole ratios of [Na2SO4 anh.]/[H2O]=0.25–0.75.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02265812

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10

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Interactions of some polar compounds with methylsilicone liquid phases in gas chromatography (1984)

Masłowska, J. ; Nowicka, K.

Springer

Chromatographia 18 (1984), S. 202-204

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ISSN: 1612-1112

Keywords: Gas chromatography ; Polysiloxane stationary phases ; Heat of adsorption ; Heat of solution

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary The changes in the heat of solution of polar compounds and xylene isomers in methylsilicone fluid OV-101 deposited on Chromosorb W AW DMCS were studied. It was shown that the heat of solution increases with an increase of the percentage loading of the OV-101 up to 10%. Solution and adsorption thermodynamic characteristics of the studied system are briefly discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02276733

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11

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Investigation of interaction of olefin-bonded transition metal complexes by gas chromatography. Diphenylphosphine complexes with CoCl2 and CoBr2 (1984)

Wasiak, W. ; Szczepaniak, W.

Springer

Chromatographia 18 (1984), S. 205-210

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ISSN: 1612-1112

Keywords: Gas chromatography ; Metal complexes ; Chemically bonded phase

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary Packings consisting of diphenylphosphine complexes with CoCl2 and CoBr2, chemically bonded to the silica surface, were synthesized and their retention parameters determined. The packings are capable of specifically interacting with electron-donating compounds by forming π-complexes. The interaction is considerably stronger in the case of CoBr2-containing packing than in the case of CoCl2-containing packing.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02276734

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12

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On-column injection in the stopped-flow mode with open-tubular columns (1984)

Pacholec, F. ; Poole, C. F.

Springer

Chromatographia 18 (1984), S. 234-238

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ISSN: 1612-1112

Keywords: Gas chromatography ; Open-tubular columns ; On-column injection ; Stopped-flow operation

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary A simple, inexpensive, on-column injector of the septum moving-needle kind is described for quantitative analysis using open-tubular columsn. when operated in the stopped-flow mode an improvement incolumn efficiency is observed combined wit a diminished tendency to produce split-top peaks, particularly for late eluting peaks. Using electronic integration a relative error of about 2.7% was observed for peaks spanning a wide range of sample concentrations and volatilities.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02270556

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13

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Viscosity of gases used as the mobile phase in gas chromatography (1984)

Ettre, L. S.

Springer

Chromatographia 18 (1984), S. 243-248

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ISSN: 1612-1112

Keywords: Gas chromatography ; Carrier gas ; Viscosity ; Influence of temperature

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract The vicosity-temperature relationship of the three gases (helium, nitrogen and hydrogen) most frequenly used as the carrier gas in gas chromatography is studied. Based on available data, equaitions are derived to describe this relationship. Using these equations viscosity data are tabulated for the chromatographically important temperature range.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02270558

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14

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Gas chromatographic determination of parabens in various pharmaceutical dosage forms (1984)

Croo, F. ; Schutter, J. ; Bossche, W. ; [et al.]

Springer

Chromatographia 18 (1984), S. 260-264

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ISSN: 1612-1112

Keywords: Parabens and their dissolution ; Pharmaceutical dosage forms ; Derivatization ; Gas chromatography

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary A specific, sensitive and general applicabla gas chromatographic method is described for the determination of parabens in various liquid pharmaceutical preparations: propylparaben and butylparaben in a liquid antacid dosage form (I); methylparaben, ethylparaben and propylparaben in a syrup (II); methylparaben and propylparaben in a solution for injection (III). Each time one of the parabens is used as internal standard. The parabens are extracted with diethylether and derivatized by silylation. Different columns are used for the analysis of the parabens: 3% SE-30 column, a 3% QF-1 column for different selectivity, a 2% OV-1 column for isothermal operation. Special attention is attributed to the standard: the parabens are dissolved in a minimal amount of 0.1 M sodium hydroxide and extracted in the same way as the pharmaceutical dosage form.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02270561

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15

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Resolution and assignment of the configuration of secondary aliphatic alcohols by gas chromatography on chiral phase (1984)

Binet, S. ; Dreux, J. ; Longeray, R.

Springer

Chromatographia 18 (1984), S. 294-296

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ISSN: 1612-1112

Keywords: Gas chromatography ; Configuration ; Resolution ; Alcohols

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary The study of the resolution of sixteen secondary aliphatic alcohols by gas chromatography on (+)-dodecyl (2R, 3R)-tartrate, trapping the ascending part of the peak from a conventional filled column, has allowed the determination in a single operation of the sign and order of emergence of enantiomers. A correlation between the configuration of these secondary alcohols and their order of emergence has been established.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02259080

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16

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Analysis of carboxylic acids by gas chromatography. Derivatisation using chloroacetone (1984)

McCalley, D. V. ; Thomas, C. W. ; Leveson, L. L.

Springer

Chromatographia 18 (1984), S. 309-312

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ISSN: 1612-1112

Keywords: Gas chromatography ; Carboxylic acids ; Acetonyl derivatives

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary The preparation of the acetonyl esters of nine aliphatic carboxylic acids is described, the general formula of the derivatives being RCOOCH2COCH3 where R=alkyl or H. The derivatives show good chromatographic properties on both packed and capillary columns. The electron impact and chemical ionisation mass spectra of the derivatives are discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02259083

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17

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A thermodynamic criterion for the identification of the functional group of aliphatic compounds by gas chromatography (1984)

Golovnya, R. V. ; Grigoryeva, D. N.

Springer

Chromatographia 18 (1984), S. 449-455

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ISSN: 1612-1112

Keywords: Gas chromatography ; Thermodynamic relationships ; Retention index ; Peak identification

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary A thermodynamic criterion, ΔQ, is suggested which permits to estimate the difference in the functional group energy of interactions for two different stationary phases. The linear dependence of ΔQ on the homolog number m of any series Rm X can be used as the thermodynamic criterion for the identification of substances by GC analysis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02262976

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18

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Performance of open tubular columns as a function of tube diameter and liquid phase film thickness (1984)

Ettre, L. S.

Springer

Chromatographia 18 (1984), S. 477-488

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ISSN: 1612-1112

Keywords: Gas chromatography ; Open tubular (capillary) columns ; Sample capacity ; Column comparison ; Film thickness ; Column diameter

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary Wall-coated, open-tubular (capillary) columns prepared from different diameter tubing, with different liquid phase film thickness, are compared with each other and with packed and support-coated open-tubular columns. The comparison is based on the variation of the phase ratio and the capacity factor, and includes column efficiency (HETP, theoretical plate number), resolution, retention time, and sample capacity. Problems associated with the evaluation of the sample capacity are outlined. The influence of temperature on column performance is discussed in detail. Finally, the possibilities of short, wide-bore open-tubular columns prepared with a thick liquid-phase film are demonstrated.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02267232

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19

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The He(Iα) Photoelectron Spectra of the Perfluoroderivatives of Trisannelated Benzenes and Tetrakisannelated Cyclooctatetraenes (1984)

Heilbronner, Edgar ; Wirz, Jakob ; Soulen, Robert L.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 47-53

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The He(Iα) photoelectron (PE) spectra of tris(perfluorocyclobuta)benzene 4(F)3,3,4,4,7,7,8,8,11,11,12,12-Dodecafluorotetracyclo[8.2.0.02,5.06,9]dodeca-1,5,9-triene, tris(perfluorocyclopenta)benzene 5(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-Octadecafluoro-2,3,4,5,6,7,8,9-octahydro-1H-trindene., tetrakis(perfluorocyclobuta)cyclooctatetraene 6(F)3,3,4,4,7,7,8,8,11,1l,l2,l2,l5,15,16,16-Hexadecafluoropentacyclo[12.2.0.02,5.06,9.010,13]hexadeca-1,5,9,13-tetraene., and of tetrakis(perfluorocyclopenta)cyclooctatetraene 7(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-Tetracosafluoro-1,2,3,4,5,6,7,8,9,10,11,12-dodeca-hydrotetracyclopenta[a,c,e,g]cyclooctene. are reported. A tentative assignment of the PE spectra is derived by empirical correlation with those of relevant reference compounds. The results suggest that 6(F) retains the D4h-conformation in the gas phase, i.e. A conformation with a planar cyclooctatetraene ring, as observed in the crystal. All four compounds exhibit a sharp increase of their first ionization energies, relative to the corresponding parent hydrocarbons, due to the perfluoro effect.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19840670107

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Transition metal complexes with bidentate ligands spanning trans-positions. Part XIVPart XIII: see [1].. Some complexes of 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene with platinum (0) and their reactivities (1984)

Boron-Rettore, Patrizia ; Grove, David M. ; Venazi, Luigi M.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 65-72

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The ligand 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) has been used to prepare complexes of the type [PtL(1)] (L = C2H4, CH2=CH—CO2Me, PhC≡CPh, MeC≡CMe, MeO2CC≡CCO2Me, (i-Pr)O2CC≡CCO2(i-Pr), Ph3P and CO). It is shown that these complexes are less labile than the corresponding species [PtL(Ph3P)2]. The preparation of complexes trans-[PtX(R)(1)] by oxidative addition of RX (RX = PhCH2Br and Mel) to [Pt(C2H4)(1)] is described. The isolation of [PtO2(CH3)2CO(1)] is also reported.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19840670109

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21

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Intermolecular Electron Spin Transfer between Naphthalene π-Systems Separated by a Variable Number of Spirobonded Cyclobutane Rings, An. ESR and ENDOR Study (1984)

Gerson, Fabian ; Huber, Walter ; Martin, Wiliam B. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 416-424

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The radical anions of the compounds N1N, N3N and N5N, in which two naphthalen π-systems are separated by 1, 3 and 5 spirobonded cyclobutane rings, respectively, and tha tof the reference compound N1, containing one naphthalene π-system and one cyclobutane ring, have been studied by ESR and ENDOR spectroscopy under a variety of experimental conditions. The intramolecular electrons spin transfer between the two π-moieties in N3N.⊖ and N5N.⊖ is slow on the hyperfine time-scale, irrespective of the applied conditions. It is also slow in N1N.⊖, except for media of high solvating power. In such media, with a slight reduction of N1N to its radical anion, a paramagnetic species is observed, the hyperfine data for which are consistent with N1N to its radical anion, a paramagnetic species is observed, the hyperfine data of which are consistent with N1N.⊖, undergoing a fast intramolecular electron spin tansfer. The ESR and ENDOR spectra of this species are superimposed on those characteristic of a slow transfer. It is suggested that the fast and slow transfer involve the syn- and anti-conformations, respectively, since the distance, r, between the two naphthalene π-systems of N1N.⊖ is considerably shorter in the former than in the latter (r = 740 vs. 880 Pm for the distance between the centres of the π-systems). Glassy solutions of exhaustively reduced N1N display signals of the dianion triplet state, whereas no such signals are found for N3N and N5N. The zero-field splitting parameter, D, is 4.7 mT, corresponding to r ≈ 480 pm.

Additional Material: 5 Ill.

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The mass spectra of organic compounds. 7th Communication6th Communication, see [1].. 4,4-Dimethyl-1-pentene (1984)

Marques, José Carlos Antunes ; Falick, Arnold ; Heusler, Andréas ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 425-433

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Loss of CH3., CH4, C2H4, C3H5., C3H6 and C3H7 from the molecular ions of a number of 13C-labeled analogs of 4,4-dimethyl-1-pentene was studied both in normal (source) 70-eV electron impact (EI) spectra dn in metastable spectra. For loss of CH3. in the source, 96% of the methyl comes frm positions of 5, 5′ and 5″, while the remainder comes from position 1. In the metastable spectra, loss of C-1 (16%) and C-3 (9%) is increasing in importance. The loss of ethylene is a particular case: either C-1 or C-3 are lost with any other C-atom from positions 2,5,5′, and 5″ (8 × 10%) in the metastable spectra, the probability for simultaneous loss of C-1 and C-3 being 6%. If C-1 seems to these two positions become completely equivalent in the metastable time range. The T-values (kinetic energy release) for the different positions show small, but statisticaly different values and a small isotope effect. Loss of C3H5 (allylic cleavage) is 100% C-1, C-2 and C-3, i.e., no evidence for skeletal rearrangement is seen. This is also true for loss of C3C6 (McLafferty rearrangement) within the source, but in metastable decay the other positions gain in importance. The neutral fragment C3H7. appears to be the the result of consecutive loss of CH3. and C3H4, rather than a one-step loss of propyl radical or the inverse reactions sequence. No metastable reaction can be seen for this reaction. Decomposition of labeled C6H11+ and C5H10+ secondary ions occurs in an essentially random fashion.

Additional Material: 6 Tab.

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Synthese von para-substituierten phenyl-terpyridin liganden (1984)

Spahni, Werner ; Calzagerri, Gion

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 450-454

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Up to now the synthesis of para-substituted phenyl-terpyridine ligands was difficult with respect to the purification of the reaction products. We have found that these compounds can easily be isolated as hydrobromides from acetic acid. Starting from the hydrobromides the purification turned out to be easy. Synthesis of para-substituted Cl-, Br-, H3C-, H2BrC-, HO- 2,6-Bis(2-pyridyl)-4-phenylphyridine is reported.

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Complexation de l'argent(I) par des teramines cycliques (1984)

Suet, Elisabeth ; Laouenan, André ; Handel, Henri ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 441-449

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Complexation of Silver(I) by Cyclic TetraminesThe nature of Ag(I)-complexes with 1,4,8,11-tetraazacyclotetradecane (1), 1,5,9,13-tetraazacyclohexadecane (2) 1,5,10,14-tetraazacyclooctadencane (3) and 1,6,11,16-tetraazacycloeicosane (4) is studied. The effect of ring size on disproportionation of the Ag() cation in the presence of ligand is reported. The stability of Ag(I)-complexes with 3 and 4 in aqueous solution is determined by means of potentiometric titration.

Additional Material: 5 Ill.

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Mitteilungen - Communications (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 625-627

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19840670231

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Masthead (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984)

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19840670301

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Radikalionen von überbrückten [14] Annulenen. Untersuchungen zum Frontorbitaleinfluss auf Reaktivität und Bindungszustand (1984)

Huber, Walter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 625-639

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Radical Ions of Bridged [14] Annulenes. Investigations on the Influence of Frontier Orbitals on Reactivity and BondingThe radical anions and the radical cations derived from trans-15, 16-dimethyl-1, 4:8,11-ethandiyliden[14]annulene (6), trans-15-methyl-1,4:8,11-ethandiyliden[14]annulene (7) and cis-15, 16-propano-1,4:8,11-ethandiyliden[14]annulene (8) are described. The hyperfine data of the radical anions 6, 7 and 8 resemble those of the structurally related radical anions of trans-10b, 10c-dimethyldihydropyrene (4) and trans-10b, 10c-dihydropyrene (5). This finding leads to the conclusion, that the change in the relative arragement of the saturated bridge within the fourteen-membered π-perimeter by passing from 4 (5) to 6 (7, 8) does not in fluence the energetic sequence of the lowest unoccupied molecular orbitals. The behavior of 6 and 7 towards oxidation parallels the photochemical reactivity of 4. The hyperfine coupling constants of the radical cations derived from 6 and 7 indicate that the removal of an electron is accompanied by an isomerization of the molecular framework. The investigation of the electron transfer process gby cyclic voltammetry supports these findings. The radical cations prefer the cyclophane-like structures 6a and 7a, in which the central σ-bond (C(15)-C(16) bond) is broken.

Additional Material: 7 Ill.

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Photochemistry of 2-(Trifluoromethyl) cyclohexanone (1984)

Semisch, Christoph ; Margaretha, Paul

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 664-668

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The photochemical behaviour of the title compound 1a is compared to that of the non-fluorinated parent ketone 2-methylcyclohexanone (1b). Substitution of the CH3- group on C(2) by a trifluoromethyl group strongly enhances 2H- and RH- reduction product formation in cyclohexane or 2-propanol and oxetane formation in the presence of 2-methylpropene as olefinic component. Under all these conditions 1b exclusively undergoes a-cleavage, a process observed for 1a only in non-reducing solvents as benzene or tert-butyl alcohol.

Additional Material: 2 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19840670305

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Synthesis of Optically Pure Compounds by Enantiotopically Differentiating Monoacetalization of Prochiral Diketones. Part II. Fragmentation of β-Keto-AcetalsPart I: [1]. These results, which have been presented in part at the ‘Herbstversammlung der Schweizerischen Chemischen Gesellschaft’, October 16, 1981, in Bern, are comprised in the Ph. D. thesis of P. M. [2]. The nomenclature and classification of stereodifferentiating reactions proposed by Izumi & Tai [3] are used in this communication (1984)

Duthaler, Rudolf O. ; Maienfisch, Peter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 832-844

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Treatment of β-keto-acetals, derived from non-enolisable β-diketones, with sulfonic acids in boiling benzene resuots in a smooth retro-Claisen-type fragmentation. The acetal-C-atom is thereby transformed into a carboxylic ester via a dialkoxycarbenium ion, which is dealkylated by the sulfonate counter-ion. Application of this reaction to the diastereomeric monoacetals 3 and 4, derived from cis-9-methyl-decalin-1,8-dione (1), followed by transesterification with CH3OH, yields optically pure 4-(2′-methyl-3′-oxocyclohexyl)butyrate 9 ((+)-9 from 3, (-)-9 from 4) and the monosulfonate of Meso-2,3-butanediol (-)-13 (Scheme 2). Unexpectedly, this cleavage proceeds as well with monoacetal 26, obtained by acetalization of trans-9-methyl-decalin-1,8-dione (27) with 2,2-dimethyl-1,3-propanediol (Scheme 7). Some attempts, aiming at an isomerization of the cis- and trans-decalin derivatives 3 and 24, or 25 and 26, via the postulated carboxonium intermediate, were not successful.

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Preparation of Bicyclo[3.3.0]octane-2,8-dione- and Declain-1,8-dione-DerivativesThese results are comprised in the Ph. D. thesis of P. M. [1] (1984)

Duthaler, Rudolf O. ; Maienfisch, Peter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 856-865

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Notes: Alkylation of bicyclo[3.3.0]octane-2,8-dione (1), which is prepared by a modification of the procedure described in the literature, gives the methyl- and propynyl-derivatives 6 and 7 (Scheme 1). In addition to the method described previously (Scheme 2), 9-methyl-cis-decalin-1,8-dione 9 is obtainable stereoselectively either by cyclization of keto-acid 16, or by aldol cyclization of keto-aldehyde 26 and oxydation of the resulting alcohols 24 and 25 (Scheme 4). The β-keto-alcohols 24 and 25 undergo a base-catalyzed isomerization; the trans-decalin isomers 27 and 28 are not detected in this equilibrium mixture (Schemes 4 and 5)l. Monoreduction of cis-dione 9 gives the endo-alcohol 25, while 27 is the favored product of the reductin of trans-dione 10 (Scheme 4). Optically pure (+)-25 can be prepared from (9S,10R)-monoacetal 29 (Scheme 5).

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Synthesis of a S-(Carboxymethyl)cysteine Analog of (L-2-Amino-6-adipyl)-L-cysteinyl-D-valine and its Cell Free Biosynthetic Conversion into 6-[2-(D-2-Amino-2-carboxyethyl)thio) acetamido]penicillanic Acid (1984)

Shields, James E. ; Campbell, Charles S. ; Duckworth, Dale C. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 870-875

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A new tripeptide (dimer), bis[(L-cysteine-S-acetyl)-L-hemicystinyl(S2 → S2)-D-valine] (6) was synthesized by coupling N-(tert-butoxycarbonyl)-S-carboxymethyl-L-cysteine benzyl ester (1) with S-trityl-L-cysteinyl-D-valine benzyl ester and subsequent removal of the protecting groups. After reduction of the disulfide, the free tripeptide Cys (CH2CO-Cys-D-Val) (Ib) was used as a substrate of isopenicillin-N synthetase in a cell-free conversion to 6-[2-((D-2-amino-2-carboxyethyl)thio)acetamido]penicillanic acid (IIa).

Additional Material: 3 Ill.

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The Synthesis of cis- and trans- 7-Phenylkacetamido-O-2-isocephemO-2-Isocephems are alternatively called isooxacephems (1984)

Hakimelahi, Gholam Hosein

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 902-905

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The synthesis of the title compounds is described.

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Erratum (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 927-927

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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URL: http://dx.doi.org/10.1002/hlca.19840670334

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Absolute Conformation and Configuration of (2S, 3S)-3-Acetoxy-5-(dimethylaminoethyl)-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one Chloride (Dilthiazem Hydrochloride) (1984)

Kojić-Prodić, Biserka ; Ružić-Toroš, ŽIva ; Šunjić, Vitomir ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 916-926

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Notes: Resolution of racemic cis-3-(2-aminophenylthio)-2-hydroxy-3-(4-methoxyphenyl) propionic acid (2) via the cinchonidine salt 3, and brucine salt 4, isolation of the calcium salts (+)- and (-)-5, as well as their cyclization to enantiomeric 1,5-benzothiazepines (+)- and (-)-1, are described. X-Ray single-crystal analysis reveals (2S, 3S) absolute configuration of (+)-1 on the basis of tentative comparison of CD data with those for the 1,4-benzodiazepine derivative (+)-8 of known absolute configuration.

Additional Material: 4 Ill.

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Masthead (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984)

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19840670401

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Synthese und Struktur von Zink-Komplexen von 2-Amino-1-azetinen (1984)

Stierli, Friedrich ; Prewo, Roland ; Bieri, Jost H. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 927-933

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Notes: Synthesis ad Structure of Zinc Complexes of 2-Amino-1-azetinesThe 2-dimethylamino-3,3-dimethyl-1-azetines 7a and 7b have been synthesized in analogy to the procedure reported by Ghosez et al. [1] (Scheme). The crystal structure of 1-benzhydryl-azetidindimethyliminium chloride 5a, a precursor of azetine 7a, has been established by X-ray diffraction analysis. Treatment of azetines 7a and 7b with ZnBr2 in CH2Cl2/MeCN yielded tetrahedral bis (azetine)dibromozinc complexes 8a and 8b, respectively (Scheme 2). The molecular structure of 8a has been determined by X-ray diffraction analysis too.

Additional Material: 3 Ill.

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Enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathiane and their olfactive properties (1984)

Pickenhagen, Wihelm ; Brönner-Schindler, Helene

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 947-952

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Notes: The enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathine 8 and 9 form (E)-2-hezen-1-ol (1) as common starting material is described. The two enantiomeric forms exhibit different organoleptic properties.

Additional Material: 2 Tab.

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Aliphatic Liquid Crystals with Positive Dielectric Anisotropy (1984)

Osman, Maged A. ; Huynh-Ba, T.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 959-963

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Cyanothyl-subsituted cylohexyl cyclohexanoates, bi(cyclohexanes) and phenyl cyclohexanes were synthisized. Their mesmorphic behaviour is compared to that of the corresponding cyano derivatives. (Cyanoethyl)cyclohexyl cyclohenxanoates show mesmorphic properties in contrast to the corresponding cyano derivative. Separation of the cyano substituent from the rigid core of an anisotropic aliphatic compound by methylene groups enhances the thermodynamic stability of the mesophase. In aromatic compound, the cyanoethyl group leads to lower clearing points. These phenomena are attributed to teh influence of steric effects on the packing density and to the dependence of the clearing point on molecular association.

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Monohaptenic Nα-Benzoyl-L-lysine Derivatives as Anaphylactogens: the Importance of the Unsubstituted Carboxyl Group (1984)

Guenin, Raymond ; Schneider, Conrad H.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1000-1002

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Notes: Nα-L-Iysine with a 2-carboxy-4, 6-dinitrophenyl (Dncp) haptenic group on the ε-amino function is a potent anaphylactogen in the guinea pig. We prepared Nε -Dncp- Nα-benzoly-L-Iysinamide and Nε-Dncp-Nα-benzoyl-L-lysyl-1-aminopropane where the carboxyl group of Iysine is blocked. Both compounds were non-elections of anaphylaxis.

Additional Material: 1 Tab.

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C45- und C50-Carotinoide. 2. Mitteilung. Synthese von optisch aktiven acyclischen C15-Endgruppen (1984)

Kramer, Andreas ; Pfander, Hanspeter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 21-28

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Notes: C45- and C50-Carotenoids. Synthesis of Optically Active Acyclic C15-End GroupsThe optically active C15-end groups (S)-12, (S)-13 and (R)-14 were prepared from the C12-synthon (S)-11 in good chemical and optical yield. These C15-end groups are suitable compounds for the synthesis of optically active C45- and C50-carotenoids.

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Interactions between Functional Groups. Part I. Crystal Structure of 2-Phenylethynyl-N,N-dimthlaniline at 98 K: A Remarkably Short C—H … C Distance (1984)

Wallis, John D. ; Dunitz, Jack D.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 39-46

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Notes: In the crystal structure of the title compound at 98 K the dimethylamino group has pyramidal geometry. The nitrogenlone pair is not directed towards the triple bond; instead, one N—CH3 bond lies almost in the plane of the disubstituted ring, directed away from the triple bond, while the other N—CH3 bond and the lone pair are directed to opposite sides of the plane, nearer to the acetylene. There is a remarkably short intramolecular contact (2.39 Å) between a methyl H- and an acetylenic C-atom. The Taft σI parameter of the arylethynyl substituent appears to be similar to that of a carboxylic ester, judging from the bond-angle deformation at the ipso-C-atom.

Additional Material: 5 Ill.

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Die Herzglykoside des Pfeilgiftes von Lophopetalum toxicum LOHER. 13. Mitteilung über Celastraceen-InhaltsstoffeAus der Dissertation von Helmut Habermeier, München, 1981. (1984)

Wagner, Hildebert ; Habermeier, Helmut ; Schulten, Hans-Rolf

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 54-64

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Topics: Chemistry and Pharmacology

Notes: The Heart Glycosides of the Arrow Poison of Lophopetalum toxicum LOHERFrom the cytotoxic and positive inotropic acting bark extract of the Philippinan Lophopetalum toxicum eight heart glycosides have been isolated and their structures have been elucidated mainly by field-desorption-MS- and 1- and 13C-NMR spectroscopy. Besides the known k-Strophanthidin (1), Antiarigenin (6) and β-Antiarin (Antiarigenin-3-β-O-α-L-rhamnoside, 10) the following mono- and diglycosides could be identified: strophanthidin-3-β-O-α-6-desoxy-D-allopyranoside (strophalloside, 2), strophanthidin-3-β-O-β-6-desoxy-D-glucopyranoside (= Strophanthidin chinovoside, 3), strophanthidin-3-β-O[-4Oβ-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (4), strophanthidin-3-β-O-[3-O-β-D-glucopyranosyl-β-6-desoxy-D-talopyranoside] (5), antiarigenin-3-β-O-[3-O-β-D-gulopyranosyl-β-6-desoxy-D-talopyranoside] (7), antiarigenin-3-β-O-[4O-β-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (8), and antiarigenin-3-β-O-β-6-desoxy-D-allopyranoside (antiallosid) (9). The structure of strophanthidinchinovoside (3) could be confirmed by synthesis.

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On the Structure of Oxirane Molecular Cation. Preliminary CommunicationDedicated to Prof. Christoph Tamm on the occasion of his 60th birthday (1984)

Bally, Thomas ; Nitsche, Stephan ; Haselbach, Edwin

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 86-90

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Keywords: Chemistry ; Organic Chemistry

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Notes: A recent controversy on the interpretation of the ESR spectrum of ionized oxirane is clarified on the basis of the electronic absorption spectra of ionized tetramethyloxirane and 9,10-octalineoxide. The results favour a ring-opened structure for oxirane molecular cation, resulting from C—C bond cleavage and being iso-π-electronic to allyl radical.

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Die Acylierung von Acetylenen mit β, γ-ungesättigten Säurechloriden. Eine neue Synthese von 5-CyclopentenonenTeilweise vorgetragen an der Versammlung der Schweizerischen Chemischen Gesellschaft am 15. Oktober 1982 in Bern; als vorläufige Mitteilung erschienen in [1]. (1984)

Karpf, Martin

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 73-85

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Notes: The Acylation of Acetylenes with β,γ-Unsaturated Acid Chlorides, A New Synthesis of 5-Substituted 2-CyclopentenonesThe acylation of acetylenes with α,α-disubstituted, β,γ-unsaturated acid chlorides under Friedel-Crafts-type conditions leads to 5-substituted 2-cyclopentenones. Phenols are formed with β,γ-unsaturated acid chlorides bearing at least one α-H-atom. These transformations are explained by the intramolecular cyclization of the initially formed vinyl cation, which, in the cases of α,α-disubstituted acid chlorides, is followed by ring contraction. The reaction leading to 2-cyclopentenones is applied to the synthesis of some spiro[4.4]nona- and spiro[4.5]deca-2,6-dienones.

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Palladium-promoted Cyclization of Tetra-alkylated 1-Arylazonaphthalenes to 2-Aryl-benzo[g]indazoles (1984)

Hugentobler, Max ; Klaus, Alfred J. ; Ruppen, Peter ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 113-119

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Notes: 1-Arylazonaphthalenes with all the potential cyclopalladation sites (one peri- and three ortho-positions) substituted by methyl or ethyl groups react with stoicheiometric or catalytic amounts of sodium tetrachloropalladate(II) to the corresponding 2-arylbenzo[g]indazoles. Possible mechanisms for the catalytic cyclization reaction are proposed.

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Photochemical reactions. 132nd communication131st Communication, see [1]. Photochemistry of 5,6-epoxy-5,6-dihydro-7-methyl-β-ionine: Influence of a methyl group at the enone side chain on the oxirane cleavagePresented in Part by B. F. at the IXth IUPAC Symposium on Photochemistry, July 25-30 1982, Pau (France). (1984)

Siewnski, Antoni ; Henggeler, Barbara ; Wolf, Hans Richard ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 120-128

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Notes: 1n, π*-Excitation of the γ,δ-epoxy-enone (E)-3 leads exclusively to the conformers (Z)-3A + B. On 1π, π*-excitation of (E)-3, in addition to (Z)-3A + B, products 6-9 arising from a carbene intermediate e are formed. However, products of an isomerization via C(γ), O-bond cleavage of the oxirane were not formed on either mode of excitation. On thermolysis, at 80° the conformer (Z)-3A is transformed into (Z)-3B, which on photolysis returns to (Z)-3A and (E)-3. At 160°, however, (Z)-3B rearranges to the isomers 6, 10 and 11.

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Selective Photoinduced Oxidation of Benzylic Methylen Groups through UV Irradiation in Presence of Ferric Chloride (1984)

Barbier, Michel

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 866-869

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Selective oxidation of benzylic methylene groups through UV irradiation in acetone/water/FeCl3 mixtures is reported. This method applied to a series of model compounds, provides an easy access to the corresponding 1-oxo derivative. Thus, tetralin gives a 100% yield of 1-tetralone, indane leads to 60% of 1-indanone, and diphenylmethane is oxidized to benzophenone with 80% yield. However, under the same conditions, alkyl-substituted aromatic hydrocarbons such as toluene, ethyl- and propylbenzene lead to low yields of aldehydes or ketones. Isochromane furnishes a mixture of two substances which can be interconverted, namely the expected l-isochromanone (9%) and the corresponding hydroxy acid (23%). We failed to apply the method to nitrogen heterocycles containing benzylic groups such as 1,2,3,4- and 5,6,7,8-tetrahydroquinoline as they do not react due to the formation of complexes which precipitate from the solutions.

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High performance liquid chromatography (HPLC) of natural products part VI.For part V, see [1] Sulfoxides of penicillin N and cephalosporin c and their role in biosynthesis of β-lactam antibiotics (1984)

Kukolja, S. ; Miller, R. D. ; Duckworth, D. C. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 876-884

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Notes: Pure pencillin N α-sulfoxide (1) and penicillin N β-sulfoxide (2) were obtained by HPLC and tested as substrates for deacetoxycephalosporin C synthetase (DXCS). Neither one of the sulfoxides was utilized under conditions of conversion of penicillin N (8) to deacetoxycephalosporin C (9). The cephalosporin C α and β-sulfoxides (3 and 4, resp.) were also prepared. Relative stabilities of the sulfoxides 3 and 4 are discussed by interpretation of the 13C-NMR spectra.

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Die Busseine C, D, E, F, G, H, J, K, L und M, zehn neue Tetranortriterpene aus Entandrophragma bussei Harms.Herrn Prof. D.A.H. Taylor, University of Natal, Durban, Natal, South Africa, danken wir bestens für die Überlassung von Extrakten. (1984)

Guex, Matthias ; Tamm, Christoph

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 885-901

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Notes: The Business C,D,E,F,G,H,J,K,L und M, Ten New Tetranortriterpenes from Entandrophragma Bussei HarmsTen new tetranortriterpenes, busseins C, D, E, F, G., H, J, K, L and M have been isolated from the petroleum ether extract of the timber of Entandrophragma bussei Harms. utilizing separation by high-pressure liquid chromatography (HPLC). The structural assignments are based mainly on spectral evidence. For the 1H-NMR spectroscopy extensive use of nuclear Overhauser effects (NOE) was made.

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Mitteilungen-Communiacations (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 928-930

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Keywords: Chemistry ; Organic Chemistry

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The Synthesis and Application of Novel Nitrating and Nitrosating AgentsWork supported by the Shiraz University Research Council. (1984)

Hakimalahi, Gholam H. ; Sharghi, Hashem ; Zarrinmayeh, Hamide ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 906-915

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Notes: Alcohols and phenols are efficiently nitrated with thionyl chloride nitrate or thionyl nitrate, even in the presence of an aromatic moiety. While thionyl chloride nitrate is suitable for nitration of primary OH-groups in carbohydrates, thionyl nitrate is reactive enough to react with secondary OH-groups as well. These reagents permit the highly selective nitration of the 5′-,2′5′- and 3′, 5′-OH-groups of ribonucleosides to produce either mono-or diprotected nitro derivatives in high yields. Carbon acids and the enol form of some ketones are efficiently nitrated with trifluoromethanesulfonyl nitrate/potassium tert-butoxide. Lutidine N-oxide (2,6-(CH3)2C5H3N O) was found to have a marked effect on nitration reactions. Similarly, thionyl chloride nitrite and thionyl nitrite exhibit an excellent capacity for nitrosation of the aforementioned substrates.

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Radical Ions of Conjugated Polycyclic Hydrocarbons Containing Two Phenalenyl π-Systems (1984)

Gerson, Fabin ; Knöbel, Jürgen ; Metzger, André ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 934-938

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Notes: The radical cations and the radical of 1,2-bis(phenalen-1-ylidene)ethane (1), 1,2-bis(phenalen-1-ylidene)ethene (2) and pentaleno[1,2,3-cd: 4,5,6-c′ d′]diphenalene (3) have been characterized by ESR and ENDOR spectroscopy. The ease of formation of these radical ions and their π-spin distributions are interpreted in terms of a simple model correlates the frontier orbitals of 1, 2 and 3 with the nonbonding MO's of two phenalenyl π-systems.

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The Synthesis and Reactions of 1-(2-Propynyl)pyidinium Salts (1984)

Katritzky, Alan R. ; Schwarz, Otto A. ; Rubio, Olga ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 939-946

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Notes: The synthesis of 1-(2-propynyl)pyridinium salts 3 described. Compounds 3 react with a second pyridine molecule, in the presence of the corresponding hydrochloride, to form products of type 4, Certain bases cause the 1-(2-propynyl)pyridinium salts 3 to rearrange into 1-propadienylpyridinium salts. 5. Diethylamine converts compounds 3 into 1-acetonylpyridinium salts 8. Moreover, treatment of 3 or 5 with sodium methoxide gives enol ether sof type 9, which can be hydrolyzed to teh ketones 8. Addition of bromine to some of teh unsaturated compounds is also reported.

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HNO, an Intermediate in (Light-induced) Rearrangement Reactions of Nitrosooxy Compounds and Nitrosamines (1984)

Müller, René-Pierre ; Murata, Shigeo ; Nonella, Marco ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 953-958

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Notes: IR-spectroscopic investigations of light-induced rearrangement reactions of nitrosooxymethane (CH3ONO3), nitrosooxyethane (CH3CH2ONO) and N,N-dimethylnitrosamine ((CH3)2NNO) in low-temperature rare-gas matrices have established that these molecules are transformed in two photolysis steps to the previously unknown C-nitroso compounds nitrosomethanol (CH2(OH)(NO)), 1-nitrosoethanol (CH3CH(OH)(NO)), and methyl(nitrosomethyl)amine CH2(NO)(NH)(CH3). Evidence for a similar rearrangement reaction has been advanced for N-Nitrosopyrrolidine which is converted to C-nitrosopyrrolidine . The matrix-isolation technique in combination with wavelength-selective irradiation allowed to trap and characterize an intermediate of rearrangement which revealed to be nitroxyl (HNO) complex (CH2…HNO, CH3CHO…HNO, CH3N = CH2…HNO, and ). Since these findings have a close resemblance with rearrangement reactions of more complex nitrosooxy compounds, nitrosamines, or nitrosohydrazines used in organic synthesis, it is suggested that also in these reactions nitroxyl is present as an intermediate species.

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1,2-Epoxycarotinoide. 3. Mitteilung. Isolierun von 1,2-Epoxy-1,2-dihydrolycopin aus Tomaten (1984)

Berset, Daniel ; Pafander, Hansperter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 964-967

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Notes: 1,2-Epoxycarotenoids: Isolation of 1,2-Epoxy-1,2-dihydrolycopene from TomatoesThe optically active, 1,2-epoxy-1,2-dihydrolycopene was isolated from tomatoes. Its constitution was established by comparison with the racemic synthetic compound.

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1,2-Epoxycarotinoide. 4. Mitteilung. Synthese, 1H-NMR- und CD-Studien von (S)-1,2-Epoxy-1,2-dihydrolycopin und (S)-1′,2′-Epoxy-1′,2′-dihydro-γ-carotin (1984)

Kamber, Matthias ; Pfander, Hanspeter ; Noack, Klaus

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 968-985

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Notes: 1,2-Epoxycarotenoids: Synthesis, 1H-NMR and CD Studies of (S)-1,2-Epoxy-1,2-dihydrolycopene and (S)-1′,2′-Epoxy-1′, 2′ -dihydro-γ-caroteneThe synthesis of (S)-1,2-epoxy-1,2-dihydrolycopene ((S)-1) and (S)-1′, 2′ -epoxy- 1′, 2′ -dihydro-γ-carotene ((S)-2) are described. The CD spectra of the (all-E)-isomers and of the isomers (7Z, S)-1 and (7′Z, S)-2 are discussed. The comparison of the CD spectra of the synthetic (S)-1 and the compound isolated from the tomatoes proves the (S)-configuration of the natural product.

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Plectranthone A, B, C und D. Diterpenoide Phenanthren-1,4-dione aus Blattdrüsen einer Plectranthuus sp. (Labiatae) (1984)

Alder, Alfredo Carlos ; Rüedi, Peter ; Eugster, Conrad Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1003-1011

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Notes: Plectranthons A, B, C, and D. Diterpenoid Phenanthrene-1,4-diones from Leaf-glands a Plectranthus sp. (Labiatae)The following structures of four new 1,4-phenanthraquionones, isolated in minute amounts from the coloured leaf-glands of a Plectranthus sp. obtained from the borders of Lake Kiwu2, Rwanda, are proposed: plectranthon A (1; 3-hydroxy-5, 7,8-trimethyl-2-(2-propenyl)phenanthrene-1, 4-dione), plectranthon B (2; 2-(2ξ-acetoxypropyl)-3-hydroxy-5,7,8-trimethylphenanthrene-1,4-dione), plextranthon C (3; 3-hydroxy- 7,8-diemethyl-2-(2-propenyl)phenanthrene-1,4-dione), and plectranthon D (4; 3-hydroxy-7,8,10-trimethyl-2-(2-propenyl)phenanthrene-1,4-dione). 2-(2ξ-Hydroxypropyl)-3,6-dihydroxy-5,7,8-trimethylphenanthrene-1,4-dione (11), a compound very similar to 1-4, was prepared by a Wagner-Meerwein, rearrangement of coleon E (5). Biogenetically, the plectranthons are derived from abietanoic precursors. The compounds 1, 2 and 4 are the first natural C20-phenanthrenes of diterpenoid origin.

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Stereoselective Control in the Base-Catalyzed H/D Exchange of 5,6-Dimethylidene-2-bicyclo[2.2.n]alkanone Tricarbonyliron Complexes. Revision of the Structures of Tricarbonyliron Complexes of 5,6-Dimethylidenebicyclo[2.2.2]oct-2-ene and 5,6-Dimethylidenebicyclo[2.2.1]hept-2-eneA preliminary communication was presented at the Autumn Meeting of the Swiss Chemical Society, Bern, October 14, 1983. (1984)

Barras, Charls A. ; Roulet, Rymond ; Carrupt, Pierre-Alain ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 986-999

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Notes: Oxidative hydroboration of exo- (1) and end-Fe(CO)3 (2) complexes of 5,6-dimethylidenebicyclo[2.2.2]oct-2-ene are highly stereoselective and give endo -alcohol 3 and exo -alcohol 4 as major products, respectively, Collins oxidations of 3 and 4 furnish the corresponding exo -Fe(CO)3 -complexed 5,6-dimethylidene-2-bicyclo-[2.2.2]octanone 7 and 8. NaBH4 reduction of exo-complexes 7 gives a mixture of 3 and isomeric exo-alcohol 18, whereas reduction of endo-complexes 8 gives the endo-alcohol, endo-complexes 19, as the sole product. The base-catalyzed H/D exchange of 7 and 8 afford the dideuterated exo-complex 35 and the monodeuterated endo-complex 32, respectively. Oxidative hydroborations of the exo-(9) and endo-Fe(CO)3 (10) complexes of 5,6-dimethylidenebicyclo[2.2.1]hept-2-ene give the corresponding exo-alcohols 39 and 40. Oxidation of 39 and 40 gives the exo- and endo-complexes 41 and 42, respectively, of 5,6-dimethylidene-2-bicyclo[2.2.]heptanone. Only Hexo —C(3) can be exchanged in 42, wheres both H-atoms at C(3) in 41 are exchangeable. The endo-Fe(CO)3 group in 8 and 42 blocks the base-catalyzed H/D exchange of Hendo —C(3), thus providing a test for the configuration of Fe(CO)3 group in these systems. These studies have led to a revision of the iron configurations proposed by Hansen et al, [2] for 1, 2, 9 and 10.

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Mitteilungen - Communications (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 361-364

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Keywords: Chemistry ; Organic Chemistry

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URL: http://dx.doi.org/10.1002/hlca.19840670143

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Parallelism Between Nucleophilically Solvent-Assisted and Phenyl-Assisted Reactions. Possible Existence of Nucleophilically β-Phenyl-Solvated Ion Pairs (1984)

Laureillard, Jeane ; Casadevall, André ; Casadevall, Eliette

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 352-360

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Notes: Solvolysis rate constants in MeOH and t-BuOh are compared for β-methyl and β-phenyl derivatives of two cycloakyl systems. It appears that the β-phenyl derivatives solvolyse at te same rate as the β-methyl ones. The lack of deceleration is attributed to phenyl assistance. It is established by configurational analysis of the reaction products, that those products which necessarily originate from a cationic species are the most abundant ones. It is suggested that these reactions could proceed through ion-pair intermediates, which are nucleophilically solvated by phelyl or by the solvent. A parallel between phenyl assistance and ‘SN2 (intermediate)’ mechanism, suggested by Bentely & Schleyer, is drawn.

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Percolative Phenomena in Microemulsions of the ‘One-Component Macrofluid’ Type (1984)

Eicke, Hans-Friedrich ; Hilfiker, Rolf ; Holz, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 361-372

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Notes: The temperature dependence of the water self-diffusion coefficients (D), as well as those of low- and high-field (stationary and time-dependent) specific conductivities (K), have been determined in the percolation regime of ternary mixtures of water, AOT, and oil. For the first time a pronounced similarity in the behavior of D and κ was detected giving instructive hints about the large variations in the specific conductivities of these systems. Results from kinetic and stationary experiments are consistent with a network-structure model of micro phases in the percolation regime in which the micro phases retain their discrete character.

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Synthèse facile de dérivés du diphényl-2,4-aza-3-bicyclo[3.3.1]nonane et du diphényl-7,8-aza-8-bicyclo[4.3.1]décaneUne partie de ce travail a fait l'object d'une communication préliminaire [1]. (1984)

Campo, Carmen Del ; Martinez, Ernesto ; Trigo, Gregorio G.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1291-1297

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Notes: Facile synthesis of derivatives of 2,4-diphenyl-3-azabicyclo[3.3.1]nonane and 7,9-diphenyl-8-azabicyclo[4.3.1]decaneThe facile synthesis of hydantoins, cyanhydrins and aminonitriles derived from 2,4-diphenyl-3-azabicyclo[3.3.1]nonanone and 7,9-diphenyl-8-azabicyclo[4.3.1]decanone is described. Configurations at C(9) or C(10) of the new compounds wth pharmaceutical and synthetical utility is deduced from their spectral properties.

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Fragmentation of 6-Deoxy-6-halo-hexono-1,5-ortholactones: A Concerted, Nonstereospecific Process (1984)

Bernet, Bruno ; Vasella, Andrea

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1328-1347

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Notes: The synthesis of the D-arabino- and D-ribo-ortholactones 13a-f and 15b-f and their treatment with Zn leading to the unsaturated esters 14a-d and 16a-d are described. Possible fragmentation mechanisms are discussed. The results were only compatible wit a concerted, nonsynchronous process, where both the axial lone pair of the ring oxygen atom and the lone pair formed during rupture of the C(5), O-bond participate in the elimination of the axial and of the equatorial C(1)-alkoxy groups, respectively.

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Electron-Transfer-Induced Conformational Changes. The Example of 1,8-Dimethyl[14]annulene (1984)

Huber, Walter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1368-1373

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: This communication reports ESR-spectroscopic investigations of the radical anion of 1,8-dimethyl[14]annulene (1) which possesses a flexible molecular framework allowing configurational and conformational mobility. The ESR and ENDOR spectra indicate that at higher temperatures (T 〉 160 K), \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{- \atop \dot{}} $\end{document} exists as a mixture of several distinct isomers. One of them, the sole product at T 〈 160 K, is found to be energetically preferred. The configuration and the conformation of this species can be determined by interpretation of the hyperfine data in terms of a singly occupied MO of the 14-membered π-perimeter.

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Dimers of 3,7-dehydrotroponesFor this nomenclature, see [1a]. (bicyclo[3.2.0]hepta-1(7),2,4-trien-6-ones) (1984)

Szechner, Barbara ; Rey, Max ; Dreiding, André S. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1386-1396

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Notes: 2-(tert-Butyl)-3,7-dehydrotropone (7-(tert-butyl)bicyclo[3.2.0]hepta-1(7),2,4-trien-6-one; 1) was found to dimerize reversibly to 2A by [2 + 4]-cycloaddition/cycloreversion reaction. The equilibrium lies on the side of the highly strained dimer 2A in the solid state, and on the side of the monomer 1 in solution. The [2 + 4]-reaction is fully perisite-, regio- and stereoselective. Above room temperature, 1 irreversibly formed a decarbonylated dimer 6, probably via the intermediate 9A or 9B, which resulted either from a dimerisation of 1 by [4 + 6]-cycloaddition or from a sigmatropic rearrangement of the originally formed dimer 2A or 2B. Similary, the 6-bromo derivative 14 afforded the corresponding decarbonylated dimer 15. Should the formation of 6 and 15 be due to a primary cycloaddition then that reaction is fully peri-, site- and regioselective. Mild LiAlH4-reduction of 6 and subsequent acetylation yielded the acetate 11, the structure of which was established by an X-ray analysis. More vigorous LiAlH4-treatment also reduced the terminal fulvenoid double bond of 6 and acetylation of the crude product led to the acetated 12 and 13.

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Mitteilungen - Communications (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1427-1428

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19840670530

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Elektromotorisches Verhalten von Flüssigmembranelektroden-Messketten mit enantiomerenselektiven chiralen Ionophoren (1984)

Morf, Werner E. ; Bussmann, Walter ; Simon, Wilhelm

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1427-1438

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Electromotive Behaviour of Liquid-membrane Electrode Assemblies Based on Enantiomer-selective Chiral IonophoresA comprehensive theoretical treatment is given for the potentiometric behavior of enantiomer-selective membrane electrodes based on chiral ionophores and plasticizers. The membrane model allows for free and complexed enantiomeric or racemic ions (e.g. ephedronium and l-phenylethylammonium ions) as well as for achiral interfering ions. Experiments are derived for the determination of the stoichiometry and the relative stability of enantiomeric ion/enantiomeric ligand complexes, and for the analytical measurement of the enantiomeric excess of ions in solution.

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Water-Exchange Mechanism of Tetraaquapalladium(II). A Variable-Pressure and Variable-Temperature Oxygen-17 NMR StudyPart 23 of the series ‘High-Pressure NMR Kinetics’. For part 22, see [1]. (1984)

Helm, Lothar ; Elding, Lars I. ; Merbach, André E.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1453-1460

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Water exchange of square-planar Pd(H2O)24+ has been studied as a function of temperature (240 to 345 K) and pressure (0.1 to 260 MPa, at 324 K) by measuring the 17/O-FT-NMR line-widths of the resonance from coordinated water at 27.11 and 48.78 MHz. The following exchange parameters were obtained: k298ex = (560 ± 40) s-1, ΔH* = (49.5 ± 1.9) kJ mol-1, ΔS* = - (26 ± 6) J K-1 mol-1 and ΔV* = - (2.2 ± 0.2) cm3 mol-1. The values refere to an aqueous perchlorate medium with an ionic strength between 2.0 and 2.6 m and a perchloric-acid concentration between 0.8 and 1.7 m, and are interpreted in terms of an associative (a) activation for the exchange. The exchange rate for Pd(H2O)24+ is 1.4 × 106 times faster than for Pt(H2O)24+ at 298 K. A comparison with reactions between other nucleophiles and Pd(H2O)24+ is also made.

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Etudes sur les composés organométalliques partie XXPartie XIX, v. [5]. Sélectivité de l'addition 1,4 de composés benzyliques du titane IV avec la benzylidéneacétone (1984)

Roulet, Daniel ; Capéros, José ; Jacot-Guillarmod, André

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1475-1477

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Notes: Studies of Organometallic Compounds, XX. Selectivity of 1,4-Addition of Benzyltitanium Compounds with BenzylildenacetoneTetrabenzyltitanium and dialkoxydibenzyltitanium compounds give essentially 1,4- addition with trans-4-phenyl-3-buten-2-one.

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Aminierende, reduktive Kupplung aromatischer Aldehyde mit Tris(dialkylamino)methylvanandium (IV) zu N,N,N′,N′-Tetraaalkyl-1,2-diaryläthylendiaminen (1984)

Imwinkelried, René ; Seebach, Dieter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1496-1502

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Notes: Aminative Reductive Coupling of Aromatic Aldehydes to N,N,N′,N′-Tetraalkyl-1,2-diarylethylenediamines, Induced by Tris(dialkylamino)methylvanadium (IV)In a novel type of reaction, certain aromatic aldehydes (benzaldehyde, p-methoxybenzaldehyde, 1-naphthaldehyde, furan-2-carbaldehyde) and secondary amines are coupled to give N,N,N′,N′-tetraalkyl-1,2-diarylethylenediamines 1-6. The reagents are tris(dialkylamino)methylvanadium(IV) compounds (cf. Eqn. 2). These are generated in situ either from isolable chlorotris(dialkylamino) vanadium(IV) (Eqn. 3), or preferably, from an Et2O/pentane solution of VCl4 which is treated sequentially with 3 equiv. of lithium dialkylamide, 1 equiv. of MeLi, and 0.8 equiv. of an aromatic aldehyde, to give the products 1-6 in a one-pot preparation (Scheme 2). The yields range from 14 to 54%. The diastereoisomeric mixtures (meso- and (±)-forms) obtained are separated by chromatography (Al2O3, petroleum ether/Et2O/Et3N), and the pure stereoisomers fully characterized. A mechanism of the reductive coupling induced by CH3V (NR2)3 is proposed (Scheme 1).

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Functionalized Cycloheptanes from Bicyclo[4.2.1]nonanes (1984)

Huston, Rima ; Rey, Max ; Dreiding, André S.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1506-1514

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Notes: Several oxidative, reductive and C,C-cleavage reactions were performed starting from the three bicyclo[4.2.1]nona-3,7-diene-2-one derivatives 1, 5 and 18. The oxidations were selective and led to the diols 2,8 and 9, and the epoxides 6,9, and 20. The reductions were selective only in the case of 20 21; otherwise they led to mixtures of the alcohols 10 and 11, and of the dienes 14 and 15. The periodate ring cleavages afforded the functionalized cycloheptane derivatives 3, 12, 13 and 16. Configurational assignments were made on the basis of detailed 1H-NMR and X-ray analysis of 20.

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Drüsenfarbstoffe aus tropischen Labiaten: Parviflorone aus Plectranthus strigosus BENTH. (1984)

Alder, Aldredo Carlos ; Rüdi, Peter ; Eugster, Conrad Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1531-1534

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Notes: Red-Coloured Abietanoids from Leaf-Glands of Plectranthus strigosus BENTH.Chromatographic examination of the red-coloured diterpenoids from the South-African title plant yielded the following compounds: parviflorone A(1), parviflorone B (2), parviflorone C(3), parviflorone E (4) parviflorone D (5), parviflorone F (6), parviflorone G (7), and parviflorone H (8). Compounds 7 and 8 represent new variants of these quinone methides.

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Drüsenfarbstoffe aus Labiaten: Die polaren Diterpenoide aus Plectranthus argentatus S. T. BLAKEVorangehende Arbeiten s. [1] [2] und darin zitierte frühere Publikationen. (1984)

Alder, Alfredo Carlos ; Rüdi, Peter ; Eugster, Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1523-1530

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Notes: Polar Diterpenoids from Leaf-Glands of Plectranthus argentatus S. T. BLAKEFrom the red leaf-glands of the Australian Plectranthus argentatus the following novel diterpenoids were isolated: coleon-U-quinone (1), 8α,9α-epoxycoleon-U-quinone (3), 6β-formyloxy-7α-hydroxyroyleanone (7), and 5,6-dihydrocoleon U (10), besides the already known compounds 6β, 7α-dihydroxyroyleanone (4), 7α-acetoxy-6β-hydroxyroyleanone (5), and 7α-formyloxy-6β-hydroxyroyleanone (6). Epoxydation of 1 by perborate led in 32% yield to the epoxyquinone 3.

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Deoxy-nitrosugars 8th communication7th Communication: [1]. Convenient preparation of 1-C-nitroglycosyl chlorides. Halonitro ethers from hydroxy oximes (1984)

Meuwly, Roger ; Vasella, Andrea

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1568-1571

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Notes: Partially protected 4- or 5-hydroxy-sugar oximes were transformed into 5- or 6-membered 1-C-nitroglycosyl chlorides, respectively, by reaction with NaOCl under phase-transfer conditions. With the exception of the oxidation of the gluco-derivative 1 giving the anomers 6 and 7, the reactions were completely diastereoselective.

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The synthesis and transition temperatures of benzoate ester derivatives of 2-fluoro-4-hydroxy-and 3-fluoro-4-hydroxybenzonitriles (1984)

Kelly, Stephen M.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1572-1579

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Notes: The synthesis and the liquid-crystal temperatures of sixty 4-cyano-2-fluorophenyl and 4-cyano-3-fluorophylen 4-substituted benzoates are described. The nematic-isotropic liquid transition temperatures of the most of these novel esters are only marginally lower than those of the corresponding esters containing an H-atom in place of the F-substituent. In several instances, the clearing points of the F-substiuted-phenyl esters are higher than those of the non-substituted-phenyl esters. The nematic ranges of several of the new esters are markedly broader than those of the analogous non-F-substituted-phenyl esters.

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An Example of Head-to-Head Dimerization of β4.4-Helices (1984)

Lorenzi, Gian Paolo ; Muri-Valle, Valentina ; Bangerter, Felix

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1588-1592

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Notes: 1H-NMR and vapor-pressure osmometry results are presented, which indicate the occurrence of a rapid equilibrium involving the head-to-head dimerization of β44-helices in chloroform solutions of HCO-L-Ile-(D-AIle-L-Ile)4-OMe. This equilibrium typifies the one that, in Urry's view, would be responsible for the formation and breaking down of the ion-conducting channels formed by gramicidin A in lipid bilayers.

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The synthesis and transition temperatures of ester derivatives of 2-fluoro-4-hydroxy- and 3-fluoro-4-hydroxybenzonitriles also incorporating aliphatic ring systems (1984)

Kelly, Stephen M. ; Schad, Hanspeter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1580-1587

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Notes: The synthesis and liquid-crystal transition temperatures of forty ester derivatives of 2-fluoro-4-hydroxybenzonitrile and 3-fluoro-4-hydroxybenzonitrile are reported. The esters contain the trans-1,4-disubstituted cyclohexane or the 1,4-disubstituted bicyclo[2.2.2]octane rings (some contain an additional phenyl ring). Many of the novel F-substituted esters exhibit substantially higher nematic-isotropic transition temperatures than the corresponding unsubstituted esters. The order of clearing points of these laterally substiuted esters differing only in the presence of a benzene ring and the above-mentioned rings id established.

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Synthese von neuen Morphin-Teilstrukturen des Typs 15,16-Secomorphinan (1984)

Révész, László

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1598-1602

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Notes: Synthesis of New Morphine Partial Structure 15,16-SecomorphinanThe synthesis of a new morphine partial structure, 15,16-secomorphinan, is described. One of the series, (±)-15, 16-secocyclorphan (5), has the analgesic potency of morphine and exhibits good binding to the opiate receptor.

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Diastereoselektive synthese neuartiger Mannich-BasenAusführliche Übersichten über die klassische Mannich-Reaktion: [1-4]. mittels titanderivatenÜbersichtsartikel über die Verwendung von Organotitanverbindungen in der organischen Synthese: [5-8]., vorläufige mitteilung (1984)

Seebach, Dieter ; Betschart, Clauida ; Schiess, Martin

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1593-1597

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Notes: Diastereoselective Synthesis of Novel Mannich (Bases1) through Titanium ReagentsTrichlorotitanium dialkylamino-alkoxides (2; titanates of N, O-hemiacetals) are generated either from the corresponding lithium alkoxides and titanium tetrachloride (Scheme 1) or by addition of trichloro-dialkuylamino-titanium to aldehydes. The electrophilic (dialkylamino) alkylating reagents 2 are used to convert lithium enolates to β-dialkylamino-ketones and -esters 5 (Mannich bases), see Scheme 2 and Table. One diastereoisomer of the products 5g-5p thus obtained with cyclohexenolate is formed preferentially (66-84%). The configuration of the products of this first diastereoselective version of the Mannich reaction could not yet be determined. A typical procedure for carrying out the reaction is given.

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Optical resolution of 7-oxabicyclo[2.2.1]hept-21-ene derivatives. Diastereoselectivity in the formation of cyanohydrine-brucine complexes (1984)

Black, Kersey A. ; Vogel, Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1612-1615

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Notes: A new, practical method for the optical resolution of bicyclic ketones if illusttrated by the preparation of (+)-(1R,4R)-7-oxabicyclo[2.2.1]bept-5-en-2-one ((+)-1) and (+)-(1R, 2S,4R)-2-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yul acetate ((+)-4). It involves the diastereoselective formation of a brucine complex with the corresponding cyanhydrine mixture.

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Transition metal complexes with bidentate ligands spanning trans-positions part XVPart XIV: See [1]. X-ray structural and 31P-NMR solution studies of some three-coordinate silver complexes of 2,11-bis[di(tert-butyl)phosphinomethyl]benzo[c]phenathrene and related ligands (1984)

Camalli, Merceds ; Caruso, Francesco ; Chaloupka, Stanislav ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1603-1611

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A series of three-coordinate bis(dialkylphosphinomethyl)benzo[c]phenanthrene Ag(I) complexes, alkyl= t-Bu, (1b), and cyclohexyl, (1c), anion = BF4, CIO4, CIO4, NO3, Cl, Br, I, have been prepared and thier 31P-NMR characteristics recorded. The solid state structures of [Ag(1b)Br], [Ag(1b)Cl] and [Ag(1b)CIO4] have been determined by X-ray diffraction. The Ag atom in these complexes shows distorted trigonal geometry. Selected bond lengths and angles are as follows: Ag-P = 2.463(4) Å and 2.433(5) Å, P-Ag-P=141.6(2)° in the bromo complex, Ag-P = 2.457(2) Å and 2.427(2) Å, P-Ag-P = 142.6(1)° ion the chloro complex, and Ag-P = 2.394(2) and 2.393 (2) Å, P-AG-P = 161.5(1)° in the perchlorato complex.

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Further Syntheses of Optically Active Verrucarinic Acid, 43rd Communication of Verrucarins and Roridins42nd Commun. : [1]. (1984)

Grossen, Peter ; Herold, Peter ; Mohr, Peter ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1625-1629

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Two new syntheses of verrucarinic acid (2S, 3R-dihydroxy-3-methylpentanoic acid) and its derivatives, suitably protected for the further conversion to macrocyclic trichothecenes, are described. The first one makes use of a diastereoselective alkylation of a (-)-(S)-malic acid ester and the regioselective reductin of one carboxyl function toa methyl group. The second approach involves a stereoselective addition of an allylsilane to a chiral glyoxylate.

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Steuerung der katalytischen Pyridinsynthese aus Alkien and Nitrilien durch (η6-Borinato)-Liganden am CobaltHerrn Prof. Dr. R. Köster, Mülheim a. d. Ruhr, mit herzlichen Wünschen zum 60. Geburtstag gewidmet (1984)

Bönnemann, Helmut ; Brijoux, Werner ; Brinkmann, Rainer ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1616-1624

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Control of the Catalytic Synthesis of Pyridine from Alkynes and Nitriles by the (η6-Borinato)-Nigands at Cobaltη6-Borinato groups as ligands at cobalt have unique effects on the chemo- and negioselectivity of the catalytic co-cyclization of alkynes and nitriles. The turnover number of the conversion of acrylonitrile and acetylene to give 2-vinylpyridine is considerably enhanced. Cyano compounds wih polar substitutents such as amino or thio groups can also be reacted. The homogeneous reaction of HCN with acetylene giving pyridine has been achieved for the first time.

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Chemo- and Stereoselective Coordination of 5,6-Dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene by d8- and d6-Metal Carbonyls. Diels-Alder reactivity of Dienes Perturbed by Remote Olefin Complexation (1984)

Vioget, Philippe ; Bonivento, Massimiliano ; Roulet, Raymond ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1630-1637

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The endocyclic double bond C(2), C(3) in 5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene (1) can he coordinated selectively on its exo-face before complexation of the exocyclic s-cis-butadiene moiety. Irradiation of Ru3(CO)12 or Os3(CO)12 in the presence of 1 gave tetracarbonyl [(1R,2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene)]ruthenium (6) or -osmium (8). Similarly, irradiation of Cr(CO)6 or W(CO)6 in the presence of 1 gave pentacarbonyl[(1R, 2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]chromium (10) or -tungsten (11). Irradiation of complexes 6 and 11 in the presence of 1 led to further CO substitution giving bed-tricarbonyl-ae-bis[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]ruthenium (7) and trans-tetracarbonyl[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo-[2.2.1]hept-2-ene)]tungsten (12), respectively. The diosmacyclobutane derivative cis-m̈-[(1R,3R,3S,4S)-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hepta-2,3-diyl)]bis(tetracarbonyl-osmium) (Os-Os) (9) wa also obtained. The Diels-Alder reactivity of the exocyclic s-cis-butadiene moiety in complexs 7 and 8 was found to be significantly higher than that of the free triene 1.

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Monoolefin and Diene Cycloaddition Induced by Transition-Metal Carbonyls. Cyclodimerization of 5,6-Dimethylidene-7-oxabicyclo[2.21]hept-2-ene Catalyzed by Dodecacarbonyltriosmium (1984)

Vioget, Philippe ; Bonivento, Massimiliano ; Roulet, Raymond ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1638-1646

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The products generated by heating 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene (1) with Fe2(CO)9, Ru3(CO)12, Os3(CO)12, Cr(CO)3(MeCN)3, (or W(CO)5(MeCN) or by treatment with Fe-atoms have been characterized by spectroscopic methods. Apart from the expected η2- and η4-complexes of the triene 1, condensation products are formed which arise from the formal [4 + 2]-cyclodimerization of 1 involving the endocyclic double bond of one molecule and the diene moiety of a second. The [4 + 2]-cyclodimerization is catalyzed by Os3(CO)12 in MeOH and gives 1,4-epoxy-7-methoxy-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene (15)). Fe-Atoms induce a stereoselective [2 + 2]-cyclodimerization pf 1 which involves its endocyclic double bond and produces the dimer 8.

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Synthese von 2,3-unsubstituierten, N-acylierten Indolen durch sigmatrope[3,3]-Umlagerung von O-Vinyl-N-phenylhydroxylaminderivaten (1984)

Martin, Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1647-1649

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of 2,3-Unsubstituted N-Acylindoles by [3,3]-Rearrangement of the N-Phenyl-O-vinylhydroxylamine DerivativesSummary, Treatment of N-phenylhydroxamic acids with vinylacetate in the presence of Li2PdCl4 affords 2,3-unsubstituted N-acylindoles via hetero-Cope-rearrangement of the intermediate N-O-vinylhydroxylamine derivatives.

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URL: http://dx.doi.org/10.1002/hlca.19840670634

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Mitteilugen - Communications (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1669-1669

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19840670637

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Masthead (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984)

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19840670701

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Photoreaction of (RS,SR)-3-Phenyl-6-hepten-2-ol. Benzene-Olefin Cycloadditions as a Synthetic Route to [5.5.5.5] Fenestranes. Part IIIFor part II of the series ‘Planarization of Tetracoordinate Carbon Atom’, see [1b]. (1984)

Mani, Jürg ; Cho, Jung-Hyuck ; Astik, Rameshchandra R. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1930-1941

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Irradiation of (RS,SR)-3-Phenyl-6-hepten-2-ol (3n) gave the photoproducts 6n-10n. Some reactions of 6n and 8n are reported. The regio- and diastereoselectivity observed in the photoreaction of substituted 5-phenylpentenes is discussed with respect to conformational preferences of the compounds to be irradiated.

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Benz[cd]indoles. Part III. A New Stereospecific Synthesis of Dihydrolysergic Acid and an Entry to 14-Substituted DerivativesPart of this work has been presented at the ‘Herbstversammlung der Schweizerischen Chemischen Gesellschaft’ at Berne, on October 18, 1982. (1984)

Haefliger, Walter E.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1942-1951

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A new convenient synthesis of dihydrolysergic acid is described, which allows the preparation of substituted derivatives, especially those with different substitutents in the aromatic ring. Starting from appropriately substituted 5-nitro-2-tetralones, the synthesis leads via a tricyclic isonitrile to the indole-ring closure as the last step, thus circumventing the troublesome protection/deprotection of the latter.

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Triaziridines. Part IIIPart II, see [1].. Triaziridine, azimine, and triazene: A SCF study of the energy and structure of N3H3-isomers (1984)

Nguyen, Minh-Tho ; Kaneti, Jose ; Hoesch, Lienhard ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1918-1929

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The portions of the N3H3 singlet potential energy surface corresponding to triaziridines (1), azimines (2) and triazenes (3) have been calculated by ab initio SCF using 3-21G, 6-31G, and 6-31G** basis sets. Minima and transition states were located by force gradient geometry optimization. The most important computation results are: (1) Triaziridines (1): The configuration at the 3 N-atoms is pyramidal. There are 2 stereoisomers, 1a and 1b. The c,t-isomer 1a has less energy than the c,c-isomer 1b. The 2 stereoisomerizations by N-inversion hve rather high activation energies. The N,N bonds in 1 are longer and weaker (STO-3G estimation) than in hydrazine. The N-homocycle 1 exhibits less ring strain than the C-homocycle cyclopropane or three-membered heterocycles. (2) Azimine (2): All 6 Atoms are in the same plane. There are 3 stereoisomers, 2a, 2b, and 2c. The order of ground state energies is (Z,Z) 〈 (E,Z) ≫ (E,E). The 2 N,N bond lengths correspond to multiplicity 1½. The electronic structure of 2 corresponds to a 1,3-dipole with almost equal delocalization of the 4 π-electrons over all 3 N-atoms. The negative net charge at the central N-atom is much less than that at the terminal N-atoms. Azimines should behave as π-donors in complexation with transition metals (3) Triazene (3): All 6 atoms are in the same plane. There are 2 stereoisomers, 3a and 3b. The order of ground-state energies is (E) 〈 (Z). The stereoisomerization proceeds as pure N-inversion. N-Inversion has a high energy barrier inversion at N(1) is faster than at N(2). One of the N,N bond lengths is typical for a double, the other for a single bond. The electronic structure of triazene 3 entails rather localized π- and p-electron pairs at N(1),N(2) and at N(3). Triazenes should behave as p-donors in complexation with transition metals. (4) -N3H3-Isomers: The order of ground-state energies is 3 〈 2 〈 1. The energy differences between these constitutional isomers are much larger than between the stereoisomers of each. The [1,2]-H shifts for conversions of 2 to 3 and the [1,3]-H shift for tautomerization of 3 have relatively high activation energies; both shifts can be excluded as modes of thermal, unimolecular transformations.

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The Reaction of 4-Hydroperoxy-2,4,6-trimethylcyclohexa-2,5-dienone with Acetaldehyde. Formatino of the Bis(peroxyacetal) (1984)

Jefford, Charles W. ; Bernardinelli, Gérald ; McGoran, Ernest C.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1952-1956

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The reaction of 4-hydroperoxy-2,4,6-trimethylcyclohexa-2,5-dienone with acetaldehyde using trimethylsilyl trifluoromethanesulfonate as catalyst gives 1,1′-bis[(1,3,5-trimethyl-4-oxo-2,5-cyclohexadienyl) peroxy]diethyl ether (7) in 70% yield. The structure of this unusual acetal was determined by X-ray analysis.

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The chemistry of drugs part IVPart III, see [1]., Configurations of antimalarials derived from qinghaosu: Dihydroqingyhaosu, artemether, and artesunic acid (1984)

Luo, Xuan-De ; Yeh, Herman J. C. ; Brossi, Arnold ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1515-1522

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The structures of the antimalarials dihydroqinghaosu (2), artemether (3), and artesunic acid (7a) derived from qinghaosu were elaborated by 1H-NMR spectroscopy, and supported with X-ray data obtained for 2 and 3. Several new derivatives, useful for the chemical characterization of dihydroqinghaosu (2) and artesunic acid (7a), were prepared.

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Deoxy-nitrosugars, 7th communication6th Communication: [1]. Synthesis of methyl shikimate and of diethyl phosphashikimate from D-ribose (1984)

Mirza, Sohail ; Vasella, Andrea

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 1562-1567

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The chain elongation of the deoxy-nitroribose 6 by a Michael addition to the vinyl-phosphonate 7 followed by a solvolysis gave the heptulosephosphonate 11 (87%). From 11, the key intermediates 15 and 16 (77%) were obtained by a highly diastereoselective reduction, followed by detritylation, periodate cleavage, and silylation. Methoxycarbonylation of 15 and 16 gave 17 and 18 which were converted into methyl shikimate (21; 79%) by intramolecular olefination and partial deprotection. Similarly, phosphonoylation of 16 gave 22 (99%) which was transformed into the diethyl phosphashikimate 2 (53% from 6).

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Mitteilungen - Communications (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 2029-2030

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19840670743

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Errata (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 2028-2028

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19840670742

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Masthead (1984)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984)

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19840670801

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On the Nature of the 7-Norbornadienyllithiums. Preliminary Communication (1984)

Goldstein, Melvin J. ; Wenzel, Timothy T.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 2029-2036

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Lithium reductions of 7-chloronorbornadiene and of bis(7-norbornadienyl)mercury both provide (C7H7)2Li2 (5a). This product is accompanied by C7H7Li2Cl (5c) in the first case, and by C7H7Li (5b) in the second. The theoretically anticipated properties of all three organolithiums are apparent in the consistent Cs symmetry of their hydrocarbon ligands, their protolytic destruction by 12-crown-4, and their significant J(C(7), Li) (5a, 7.6; 5b, 16.0; 5c 8.9 Hz).

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Novel Variant of the Tricyclooctanone Approach to Cyclopentanoid Natural Products. Synthesis of (±)-Coriolin. Preliminary Communication (1984)

Demuth, Martin ; Ritterskamp, Peter ; Schaffner, Kurt

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 2023-2027

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A total synthesis of the antitumor sesquiterpene coriolin (9; racemic) in 11 steps from 3,3,6-trimethylbicyclo[2.2.2]oct-7-ene-2,5-dione (2a/2b) is described (yield 2a/2b→8: 28%). The sequence is unprecedentedly short and avoids difficult separation problems. The key step in the scheme is a novel facet of oxadi-π-methane photochemistry, i.e., the steering by subtle steric effects of the β,γ-unsaturated ∊-diketone to undergo a regioselective photorearrangement involving one β,γ-enone partial chromophore. Furthermore, the overall phototransformation, which can be carried out at unusually high concentrations (≥20% solutions), involves also a Norrish type I process equilibrating the two epimeric starting enediones 2a and 2b in favour of the desired stereoisomer.

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Synthese von optisch aktiven Carotinoiden mit 3,5,6-Trihydroxy-5-6-dihydro-β-Endgruppen (1984)

Buchecker, Richard ; Marti, Urs ; Eugster, Conrad Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 67 (1984), S. 2043-2056

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Syntheses of Optically Active Carotenoids with 3,5,6-Trihydroxy-5,6-dihydro β-End GroupsFor the specification of the relative and absolute configuration in carotenoids with 3,5,6-trihydroxy-5-6-dihydro β-end groups, several ionone derivatives and carotenoids bearing this end group were synthesized. Acid-catalyzed hydrolysis of (3S,5S,6R)- acetoxy-5,6-epoxy-5,6-dihydro-β-ionone (7) and of its (3S,5R,6S)-isomer (13) gave the diols 8 and 15, respectively, with exclusive inversion at c(5) (Scheme 2). Compared to this, mild acid hydrolysis of caroten-5-6-expoxides in the presence of H2O resulted in the formation of 5,6-diols with either inversion or retention of the configuration at C(6) (Scheme 3). Spectroscopic data allowed us to distinguish the relative configurations (3R*,5S*,6S*) (see A), (3R*,5R*,6R*) (see B), (3R*,5S*,6R*) (see C), and (3R*,5R*,6S*) (see D), of the 3,5,6-trihydroxy-5-6-dihydro β-end groups. Syntheses of the optically active carotene-hexols 20 and 21 and comparison with published data led to a revision of the structure of mectrazanthin (now formulated as 20), heteroxanthin (now formulated as 28), and further carotenoids with 3,5,6-trihydroxy end groups.

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