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1

Digitale Medien

Preparation of Optically Active Secondary Amines by Thermal Decomposition of (Methylbenzyl)urea Analogs: Absolute Configuration of (+)- and (-)-Mecamylamine. Preliminary CommunicationThe full paper will be published elsewhere.Patent application has been filed. (1986)

Schönenberger, Bernhard ; Brossi, Arnold ; George, Clifford ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 283-287

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Thermolysis of the (α-methylbenzyl)urea diastereoisomers 4 and 5 of (±)-mecamylamine ((±)-1) and 6 and 7 of (±)-1-noreseroline O-methyl ether ((±)-3) in refluxing alcohol afforded optically pure amines in high yield, besides optically pure carbamates of (α-methylbenzyl)amine which can be recycled. The absolute configuration of (-)-mecamylamine hydrochloride ((-)-1 · HCl) was determined by X-ray diffraction analysis.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690205

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2

Digitale Medien

2,5-Chinonmethide des 1,6-Methano[10]annulens mit S,N- und N,N-Acylketenacetal StrukturMeinem hochverehrten Lehrer, Prof. Dr. Siegfried Hünig, Würzburg, zum 65. Geburtstag gewidmet (1986)

Neidlein, Richard ; Hartz, Georg

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 315-328

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: 2,5-Quinonemethides of 1,6-Methano[10]annulene with the Structures of S,N- and N,N-Acylketene AcetalsInvestigation on the chemical reactivities of 2-(tert -butoxy)-1,6-methano[10]annulene and the syntheses of the compounds 2, 4, 6-8, 11, 13-22 are described; the results of 1H- and 13C-NMR-spectroscopic measurements are reported.

Zusätzliches Material: 3 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690209

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3

Digitale Medien

1,2-Epoxycarotinoide. 6. Mitteilung. Isolierung von 1′,2′-Epoxy-1′,2′-dihydro-ε,ψ-carotin aus der ‘Delta-Mutanten’-Tomate (1986)

Berset, Daniel ; Pfander, Hanspeter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 340-344

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: 1,2-Epoxycarotenoids Isolation of 1′,2′-Epoxy-1′,2′-dihydro-ε,ψ-carotene from a ‘Delta Mutant’ TomatoFrom ‘Delta Mutant’ tomatoes, optically active 1′,2′-epoxy-1′,2′-dihydro-ε,ψ-carotene (7) was isolated. According to the CD data, the configuration is 6R and presumably 2′S.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690212

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4

Digitale Medien

(Cholestanyloxycarbonyl)benzyl esters as peptide substituents: Conformational properties of fully protected oligo-L-lysines with C-terminal (cholestanyloxycarbonyl)benzyl and benzyl ester moieties (1986)

Toniolo, Claudio ; Bonora, Gian Maria ; Moretto, Vittorio ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 350-358

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: This study involves L-lysine oligo peptides, protected at the N-terminus by the Nps and at the ε-amino functions by Boc groups. Two series were prepared from dimer to octamer, one containing the p-[(cholestan-3β-yloxy)carbonyl]benzyl, the other one the benzyl ester group at the C-terminus. Conformational analyses were performed by IR absorption. The occurrence of the intermolecular β-structure in the solid state and in CH2Cl2 solution was demonstrated for the highest oligomers. The relative stabilities of the self-associated species were determined by adding a variety of polar solvents to the CH2Cl2 solutions. The cholestanyl-containing peptides have a lower propensity to self-aggregate than the benzyl-ester analogues. Self-aggregation and decreasing solubility run in parallel. It was also directly shown that soluble urea derivatives may disrupt intermolecular H-bonds in CH2Cl2, a point of practical interest, particularly in solid-phase peptide synthesis.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690214

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5

Digitale Medien

Die toxischen und sedierend wirkenden Bufadienolide von Kalanchoedaigremontiana HAMETet PERR (1986)

Wagner, Hildebert ; Lotter, Hermann ; Fischer, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 359-367

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The Toxic and Sedative Bufadienolides of Kalanchoe daigremontiana HAMET et PERR.From the toxic Crassulacee Kalanchoe daigremontiana five biosynthetically related bufadienolides have been isolated and structurally elucidated by X-ray and 1H- and 13C-NMR spectroscopy. The compounds were identified as bersaldegenin 1,3,5-orthoacetate (2), bersaldegenin 1-acetate (4), bersaldegenin 3-acetate (3), 1β,3β,5,11α,14-pentahydroxy-12,19-dioxo-5β,14β-bufa-20,22-dienolide 1,3,5-orthoacetate ( = daigremontianin; 1), and 3β-acetoxy-1β,5,14-trihydroxy-5β,14β-bufa-20,22-dienolide ( = daigredorigenin-3-acetate, 5). According to the pharmacological investigations, the two orthoacetates 1 and 2 comprise the positive inotropic, sedative, and toxic activity of the plant.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690215

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6

Digitale Medien

Enantioselective Synthesis of D-erythro-Sphingosine and of Ceramide (1986)

Julina, Radomir ; Herzig, Thomas ; Bernet, Bruno ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 368-373

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The enynol 2 was transformed into D-erythro-sphingosine 11 (7 steps, 46%) and into ceramide 1 (8 steps, 41% overall yield). The key steps were the mono-epoxidation of the enynol 5 (Ti(t-BuO)4, (-)-D-diethyl tartrate, t-BuOOH) to 6 (86%, ≥ 98% ee), the regioselective intramolecular opening of the oxirane 6 via the benzylurethane 7, and the reductive tranformation of the acetylene 9 into the oxazolidinone 10 (Li, EtNH2, 88%).

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690216

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7

Digitale Medien

An ESR Study of the Radical Cations of Tetrathiafulvalene (TTF) and Electron Donors Containing the TTF Moiety (1986)

Ćavara, Luka ; Gerson, Fabian ; Cowan, Dwaine O. ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 141-151

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Hyperfine data and g factors are reported for the radical cations of tetrathiafulvalene (TTF; 1) and of its derivatives 2-13. From the intense satellite spectra of 1+-13+ not only the coupling constants of the 33S isotopes in the TTF moiety could be determined, but also, in favourable cases, those of the 13C isotopes in the central double bond. The former values range from 0.370 (8+) to 0.470 mT (4+) and the latter from 0.255 (8+) to 0.360 mT (4+) in the radical cations of bis(ethylenedithio)-TTF (8+) and tetracyano-TTF (4+). The radical cation of TTF (1+) exhibits intermediate values, 0.425 for the 33S and 0.285 mT for the 13C isotopes. The spin population in 1+-13+ resides, to a large extent, in the central S2C = CS2 part of the π-system. It tends to increase (decrease) by substitution with electron-accepting (donating) groups in the 2,3,6,7-positions of TTF.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690117

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8

Digitale Medien

Conformation-Odor Relationships in Norlabdane Oxides (1986)

Ohloff, Günther ; Vial, Christian ; Demole, Edouard ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 163-173

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Conformational factors have been found responsible for the dramatic change in odor between (-)-deoxyambreinolide (12) and its (+)-epi derivative 13. The presumably molecular event during the receptor interaction has been simulated by the diastereoisomeric 11-methyl-ambrox derivatives 3 and 5 as model compounds.

Zusätzliches Material: 1 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690120

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9

Digitale Medien

Crystal Structures of Chiral Ionophores: Bis(9,9′-spirobifluorene)-26-crown-4 and -32-crown-6 (1986)

Egli, Martin ; Dobler, Max

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 626-631

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The X-ray crystal structures of bis(9,9′-spirobifluorene)-26-crown-4βbenzene solvate (monoclinic, a = 15.47 Å, b 11.265 Å, c = 15.220 Å, β = 91.54°, space group C2) and bis(9,9′-spirobifluorene)-32-crown-6·dichloromethane solvate (tetragonal, a = 20.958 Å, c = 11.779 Å, space group P41212) are described. Both compounds act as enantioselective ionophores for α-aminoalcohols.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690312

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10

Digitale Medien

Steric Effects on Reaction Rates. Part VIII. The Significance of Front Strain Release in Solvolysis of Bridgehead Derivatives (1986)

Müller, Paul ; Blanc, Jacky ; Mareda, Jiri

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 635-645

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The steric requirements of leaving groups for 14 bridgehead derivatives have been examined using MM2 calculations. The strain varies almost monotonously throughout the series upon variation of the leaving group from H to C1, OH, CH3, CH3CH2O, (CH3)3CO, (CH3)3C and no significant trends for differential F-strain effects are detected expect for the perhydrophenalene derivative 13. The experimental rates of solvolysis of bridgehead derivatives correlate well with the calculated steric energy differences between substrate R-X and the corresponding carbenium ion R⊕. However, the strain calculations using the more recent force-fields (MM2) disagree, in part, with those reported in the literature: chloride and p-toluenesulfonate leaving groups correlate with identical slopes, and the perhydrotriquinacene derivative 10 shows no anomalous behavior. The calculations suggest that F-strain and C,C-hyperconjugation should not play any dominant role in bridgehead solvolysis.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690314

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