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  • 1
    Electronic Resource
    Electronic Resource
    Studies on the Synthesis of (2R,4′R,8′R)-α-Tocopherol Alternative Syntheses of 2-Chroman-acetic Acid Intermediates (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 837-843 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As an extension of previous studies on the total synthesis of (2R,4′R,8′R)-α-tocopherol (1) [1] [2], (S)-(-)-2-(6-benzyloxy-2,5,7,8-tetramethylchroman)acetic acid (6), a pivotal intermediate, possessing the absolute configuration required for construction of 1 was prepared by optical resolution of the racemic modification 11. the latter substance was obtained by two routes, one emanating from the hydroxy acetal 7 [1] and the other based upon the Lewis acid mediated cycloaddition of trimethylhydroquinone to rac.-3-hydroxy-3-methylpent-4-en-l-yl acetate (16) giving rac. ethyl 2-(6-hydroxy-2,5,7,8-tetramethyl-chroman)acetate (12).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610231
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  • 2
    Electronic Resource
    Electronic Resource
    Syntheses of (2R, 4′R, 8′R)-α-Tocopherol and (2R, 3′E, 7′E)-α-Tocotrienol (1976)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 59 (1976), S. 290-306 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of trimethyl-hydroquinone with methyl vinyl ketone in acidic methanol gave rac.-2-methoxy-2,5,7,8-tetramethyl-chroman-6-ol (8). This acetal was converted in four steps to rac.-(6-hydroxy-2,5,7,8-tetramethyl-chroman-2-yl)acetic acid (13). Acid 13 was readily resolved with α-methyl-benzylamine to give the (S)-enantiomer 14. Treatment of the unwanted (2 R)-isomer with acid regenerated 13, thus leading to an efficient use of this compound. Employing a side chain derived from phytol, 14 was converted to (2R, 4′R, 8′R)-α-tocopherol (1d, ‘natural’ vitamin E). A reaction sequence from 14 involving two highly stereoselective Claisen rearrangements has provided the first total synthesis of (2R,'E,7′E)-α-tocotrienol (2d).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19760590135
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  • 3
    Electronic Resource
    Electronic Resource
    Synthese von Pumiliotoxin C (1976)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1976 (1976), S. 1577-1583 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Pumiliotoxin Crac-Pumiliotoxin C (PTX-C, rac-1) is obtained in a four step stereoselective synthesis, starting from ethyl 4-methyl-2-(1-pyrrolidinyl)-l-cyclohexenecarboxylate (6) and 1-(2-bromoethyl)- butylamine hydrobromide (7), in 25 % yield. This method can easily be adapted to the syn- thesis of optically active PTX-C and of other pumiliotoxins.
    Notes: rac-Pumiliotoxin C (PTX-C, rac-1) wird in einer 4stufigen stereoselektiven Synthese, ausgehend von 4-Methyl-2-( l-pyrrolidinyl)-l-cyclohexencarbonsäure-äthylester (6) und 1-(2- Bromäthyl)butylamin-hydrobromid (7) in 25 proz. Ausbeute erhalten. Dieses Verfahren läßt sich leicht auf die Synthese von optisch aktivem PTX-C und weiteren Pumiliotoxinen übertragen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197619760906
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    Paper (German National Licenses)
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