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  • 1
    Electronic Resource
    Electronic Resource
    Heterocyclisch anellierte Pyrazin-1,4-dioxide; 1. Mitt.: Die positionsselektive Synthese von Pyrido[2,3-b]pyrazin-1,4-dioxiden (1980)
    Springer
    Monatshefte für Chemie 111 (1980), S. 407-411 
    Details
    ISSN: 1434-4475
    Keywords: Heterocyclic compounds ; Pyrazin-1,4-dioxides ; Pyrido[2,3-b] pyrazin-1,4-dioxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The positionsselective synthesis of the title compounds5 is described and the structure established by reduction of5c to8 and synthesis of the latter by an unambiguous method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00903236
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  • 2
    Electronic Resource
    Electronic Resource
    Pheromone, 1. Mitt.: (+)-cis-Disparlure: Synthese und Feldtests (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 101-110 
    Details
    ISSN: 1434-4475
    Keywords: (+)-cis-Disparlure ; Enantioselective synthesis ; Field tests ; Mating disruption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A synthesis of (+)-cis-disparlure is described starting from racemic 2-hydroxy-dodecannitrile (2), which is transformed into the O-protected enantiomerically pure cyanohydrine4. Grignardreaction followed by reduction with BH3 · (CH3)2S yields the correspondingthreo-configurated secondary alcohol10. After tosylation and cleavage of theMBE-protective-group (+)-cis-disparlure (14) is obtained by treatment with KOH. Mating disruption field tests exhibited a significantly increased effectiveness of (+)-cis-disparlure as compared to the racemic product.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00815171
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  • 3
    Electronic Resource
    Electronic Resource
    Aminoalkohole, 1. Mitt.: Ein Verfahren zur Synthese enantiomerenreiner 1,2-Aminoalkohole miterythro-Konfiguration (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 283-290 
    Details
    ISSN: 1434-4475
    Keywords: 1,2-Amino-alcohols ; Enantiomerically pure ; erythro-Configuration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The synthesis of both enantiomers of norephedrine and norisoephedrine is described to present a method for the preparation of enantiomerically pure branched 1,2-aminoalcohols. In a one pot reaction enantiomerically pure cyanohydrins bearing an acetal protective group are subjected to Grignard-reaction followed by addition of lithium aluminum hydride. After deprotection the target compounds are obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810829
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  • 4
    Electronic Resource
    Electronic Resource
    Ein Verfahren zur Synthese enantiomerenreiner Alkanole durch reduktive Entschwefelung von Thiophenalkoholen (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 705-718 
    Details
    ISSN: 1434-4475
    Keywords: Acetals ; Desulfurization ; Enantiomerically pure alkanoles ; Thiophenemethanol derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acetals3 and4 of alkylthienylcarbinols1 were prepared using an enantiomerically pure lactol2. In the key step these compounds were desulfurized. After deprotection the target compounds7 andent-7 were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811470
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  • 5
    Electronic Resource
    Electronic Resource
    Pheromone, 2. Mitt. Ein Verfahren zur Herstellung von Ketonen und Spiroketalen durch Entschwefelung von Thienylethern (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 185-194 
    Details
    ISSN: 1434-4475
    Keywords: Desulfurization ; Hydrogenation ; Ketones ; Pheromones ; Spiroketals ; Thiphene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Starting from substituted methoxythiophenes1 ketones and spiroketals can be synthesized in one step by desulfurization with partial hydrogenation. The bark beetle pheromone chalcogran2 a and the wasp anti aggression pheromone2 b were prepared by this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809364
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  • 6
    Electronic Resource
    Electronic Resource
    Pheromone, 3.Mitt.: Eine einfache Methode zur Steuerung der Reduktion von α-Alkoxy-carbonylverbindungen (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 299-317 
    Details
    ISSN: 1434-4475
    Keywords: Enantiomerically pure ; 1,2-Diols ; Stereoselective reduction ; Pheromon synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Enantiomerically pure 1,2-diols bearing optionallysyn oranti configurated secondary hydroxylic groups are synthesized from acetal-protected cyanohydrins. After resolution of the diastereomers the cyanohydrins are converted into α-alkoxy-ketones by Grignard-reaction followed by reduction using common chelating or non-chelating agents. Among others syntheses of enantiomerically pure pheromones,endo-Brevicomin,exo-Brevicomin and Dispalure are given as examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810831
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  • 7
    Electronic Resource
    Electronic Resource
    Stereoelektronische Effekte und chirale Erkennung, I. Diastereoselektive Etherbildungen aus Alkylarylcarbinolen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 359-365 
    Details
    ISSN: 0009-2940
    Keywords: Diastereoselectivity ; Effect, kinetic ; Effect, stereoelectronic ; Etherification ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoelectronic Effects and Chiral Recognition, I.  -  Diastereoselective Formation of Ethers from AlkylarylcarbinolsAcid-catalysed etherification of various alkylarylcarbinols 1 leads to a mixture of diastereomeric products 2 and 3. As found in the closely related formation of diastereomeric acetals, the ratio 2/3 is shown to be time-dependent. Preferred formation of the meso-diastereomer 3 under kinetic condition and preferred formation of the racemic diastereomer 2 under thermodynamic conditions is observed. A reaction path based on π-π interactions and stereoelectronic effects is presented to explain experimental results.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270213
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  • 8
    Electronic Resource
    Electronic Resource
    Chirale Lactole, I. Die 2,3,3a,4,5,6,7a-Octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl-Schutzgruppe (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 1576-1590 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chiral Lactols, I. The 2,3,3a,4,5,6,7,7a-Octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl Protective GroupThe preparation of the tricyclic lactones 11 and 12 starting from optically active camphor derivatives is described with several alternatives for the synthesis of 11. The lactol 20 is obtained from 11 by reduction. Lactol 20 and its derivative 21 (obtained by self-acetalisation of 20) react with a series of alcohols with high diastereoselectivity to yield the α(exo)-acetals 22.
    Notes: Die Herstellung der beiden tricyclischen Lactone 11 und 12 aus optisch aktiven Campherderivaten wird beschrieben, wobei für 11 mehrere alternative Synthesen untersucht werden. Aus 11 wird durch Reduktion das Lactol 20 erhalten. Mit hoher Diastereoselektivität lassen sich 20 und das daraus durch Selbstacetalisierung erhaltene 21 mit einer Reihe von Alkoholen zu den α(exo)-Acetalen 22 umsetzen.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150433
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  • 9
    Electronic Resource
    Electronic Resource
    Chirale Lactole, II. Racematspaltung und enantioselektive Acetalisierung mit der 2,3,3a,4,5,6,7,7a-Octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl-Schutzgruppe (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 1591-1606 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chiral Lactols, II. Racemate Separation and Enantioselective Acetalisation with the 2,3,3a,4,5,6,7,7a-Octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl Protective GroupA simple method for the resolution of the chiral alcohols, cyanohydrins, thiols and amines rac-2a-f by the reaction with the chiral protective group 1a (or 1b, respectively) is described. The diastereomeric derivatives 3a-f and 4a-f are separated by column chromatography or crystallisation. Subsequent methanolysis or hydrolysis, respectively, yields the enantiomers and the recovered protective group. With rac-2a-c preferential acetalisation of the (R)-enantiomers was observed. This phenomenon was investigated by modification of the protective group. Considerations on conformations of 3a point to an important role of the anomeric and exo-anomeric effect in this enantioselective reaction.
    Notes: Eine einfache Racemattrennung der chiralen Alkohole, Cyanhydrine, Thiole und Amine rac-2a-f durch Umsetzung mit der chiralen Schutzgruppe 1a (bzw. 1b), Trennung der diastereomeren Derivate 3a-f und 4a-f durch Säulenchromatographie oder Kristallisation und anschließende Methanolyse bzw. Hydrolyse und Rückgewinnung des Reagens 1b wird beschrieben. Bei der Umsetzung von rac-2a-c beobachtete man eine bevorzugte Acetalisierung der (R)-Enantiomeren. Die Untersuchung dieses Phänomens durch Modifikation der Schutzgruppe und konformationelle Überlegungen anhand von 3a weisen auf eine bedeutende Rolle des anomeren und exo-anomeren Effekts bei dieser enantioselektiven Reaktion hin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150434
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  • 10
    Electronic Resource
    Electronic Resource
    Chirale Lactole, III. Eine enantioselektive Alkylierung der Mercaptoessigsäure (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 1607-1616 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chiral Lactols, III. An Enantioselective Alkylation of Mercaptoacetic AcidThe enantioselective alkylation of mercaptoacetic acid (2) via the thioacetal 3 is described. The enantiomeric excess (e. e.) observed was 54% in the methylation and 60% in the ethylation reaction in favour of the (R)-form. The (S)-diastereomer was formed only in minor amounts during alkylation and could be removed by esterification of the diastereomeric acids 7 and subsequent column chromatography. Methanolysis of 7 and 8 yielded the optically active acids 9 and the methyl acetal 6, respectively, which reacted with 2 to reform the thioacetal 3. Considerations are made on the mechanism of this asymmetric alkylation.
    Notes: Die enantioselektive Alkylierung von Mercaptoessigsäure (2) über das Thioacetal 3 wird beschrieben. Bei der Methylierung wurden 54% Enantiomerenüberschuß (EE), bei der Ethylierung 60% EE zugunsten der (R)-Form beobachtet. Durch Veresterung der diastereomeren Säuren 7 und anschließende Säulenchromatographie gelang die Entfernung des bei der asymmetrischen Alkylierung in geringen Mengen gebildeten (S)-Diastereomeren. Durch Methanolyse von 7 und 8 wurden die optisch aktiven Säuren 9 bzw. das Methylacetal 6 erhalten, welches sich mit 2 wieder zum Thioacetal 3 umsetzen ließ. Überlegungen über den Mechanismus dieser asymmetrischen Alkylierung werden angestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150435
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