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  • 1
    Electronic Resource
    Electronic Resource
    Design and Synthesis of Novel Opiate Antagonists with LH-Stimulating Properties (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 326-336 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Opiate antagonists stimulate the release of LH and might, therefore, contribute to an innovative therapy for the treatment of numerous clinical syndromes characterized by hypofunction of the HHG axis. The purpose of this work was to design and synthesize pure opiate antagonists useful for this therapy. Me, Et, Pr, and PhCH2 groups were introduced at the crucial 14β-position of morphines and morphinans via a hetero-Diels-Alder key step starting from thebaine derivative 1 and tested for opiate antagonism and LH-stimulating activity. Me-, Et-, and Pr-substituted compounds 11a-c were stronger antagonists than naltrexone, whereas Pr and PhCH2 substituents in 11c, 11d, 9d, 9d3, 9d4, and 9d5 led to orally active LH stimulators. Based on our finding that the μ-antagonists 12 and 11b5 showed no LH stimulation, we conclude that a combination of both μ-and χ-antagonism is necessary for potent LH stimulation.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730212
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  • 2
    Electronic Resource
    Electronic Resource
    Ambident reactivity of aryloxide ions towards 1,3,5-trinitrobenzene, low-temperature characterization of the elusive Oxygen-bonded σ-complexes by 1H and 13C NMR spectroscopy (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 71-82 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ambident reactivity of phenoxide ion towards 1,3,5-trinitrobenzene (TNB) was re-examined by means of a novel reaction system(CD3CN-glyme-d10) which allows the investigation of species formed at low temperatures (-40°C), contrasting with previous studies in dimethyl sulfoxide (DMSO) at ambient temperature. The new method coupled with 400 MHz NMR spectroscopy has allowed the definitive observation of both O- and C-bonded phenoxide σ-complex adducts for the first time, confirming the formation of the former through kinetic control and of the latter through thermodynamic control. The corresponding O-bonded σ-adduct in the TNB-mesitoxide system (whereC-bonded σ-adduct formation is not possible but where there is competing nitro group displacement) has also been characterized by 1H and 13C NBR. Another O-bonded aryloxide adduct characterized is that from the reaction of TNB with3,5-di-tert-butylphenoxide; in this system there is also competing NO2 displacement. Stereoelectronic factors in the O-bonded σ-adducts and aryl ethers are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060202
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  • 3
    Electronic Resource
    Electronic Resource
    Lipidic peptides, I. Synthesis, resolution and structural elucidation of lipidic amino acids and their homo- and hetero-oligomers (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1175-1183 
    Details
    ISSN: 0170-2041
    Keywords: Amino acids, fatty ; Peptides, lipidic ; Drug delivery ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The α-amino acids with long alkyl side chains, the so-called lipidic amino acids 1a-e, and their homo-oligomers, the lipidic peptides 1p-aj, represent a class of compounds which combine the structural properties of peptides and proteins with the characteristics of lipids and membranes. The amino acids were synthesised from the appropriate alkyl bromide and diethyl acetamidomalonate. Resolution was made chemically, by forming diastereomers of the amino acid esters with an optically pure α-pinene derivative. The protected homooligomers were synthesised in solution with the assistance of a water-soluble carbodiimide coupling agent. In order to modify the physical and chemical properties of the peptides, a series of protected hetero-oligomers were prepared, by similar methods, incorporating either other amino acids (3a - d, 7a - i) or side-chain-substituted lipidic amino acids (6a-d).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1990199001215
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and Oral Uptake Studies of Lipidic and Glyco-Lipidic Conjugates of β-Lactam Antibiotics (1994)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1994 (1994), S. 685-688 
    Details
    ISSN: 0170-2041
    Keywords: Amino acids, lipidic ; Antibiotics ; Drug delivery ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipidic and glyco-lipidic cephalosporin conjugates 1c and 1i were synthesised as diastereomeric mixtures to improve their oral absorption. 2-(tert-Butoxycarbonylamino)tetradecanoic acid was condensed with thiazole 1d and by following basecatalysed hydrolysis of the fully protected rac-1e, the free acid rac-1f was produced. This was then used to acylate the carboxy-protected cephalosporin analog 1g by using a modified Vilsmeier reaction. Removal of the protecting groups of 1b resulted in conjugate 1c. Cephalosporin conjugate li, which contains a sugar moiety in addition to a lipidic amino acid residue, was synthesised to produce a drug conjugate with both lipophilic and hydrophilic properties [radiolabelled (14C) analogs 1a, 1c and 1i were also synthesised]. The radio-labelled parent 1a and conjugates 1c and 1i were administered orally to rats and uptake of the radiolabel in the blood, various organs, urine and faeces was determined. The results showed that an increase in lipophilicity caused an increase in the oral uptake, suggesting that conjugation to lipidic amino acids and peptides is a useful approach to the improvement of the absorption of poorly absorbed drugs.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199419940709
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