4-Dialkylaminopyridines as Highly Active Acylation Catalysts. [New synthetic method (25)]

Authors

  • Priv.-Doz. Dr. Gerhard Höfle,

    1. Organisch-Chemisches Institut der Technischen Universität, Strasse des 17. Juni 135, D-1000 Berlin 12 (Germany)
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  • Prof. Dr. Wolfgang Steglich,

    1. Institut für Organische Chemie und Biochemie der Universität, Gerhard-Domagk-Strasse, D-5300 Bonn (Germany)
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  • Prof. Dr. Helmut Vorbrüggen

    Corresponding author
    1. Research Laboratories of Schering AG, Berlin/Bergkamen, P.O. Box 650311, D-1000 Berlin 65 (Germany)
    • Research Laboratories of Schering AG, Berlin/Bergkamen, P.O. Box 650311, D-1000 Berlin 65 (Germany)
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  • 4-Dialkylaminopyridines as acylation catalysts, 4th Communication.—3rd Communication: G. Höfle, W. Steglich, Synthesis 1972, 619.

  • Pyridine syntheses, 1st Communication.—2nd Communication: H. Vorbrüggen, J. Kottwitz, K. Krolikiewicz, Chem. Ber., in preparation. This publication gives a complete survey of the various syntheses of DMAP and PPY; H. Vorbrüggen, DOS 2517774 (1975). Schering AG; Chem. Abstr. 86, 55293d (1977).

Abstract

The synthesis of 4-dialkylaminopyridines can be accomplished in two steps starting from pyridine. Compared to pyridine, these derivatives are approximately 104 times more active when used as acylation catalysts. Dialkylaminopyridines are being used with ever-increasing frequency for acylation reactions which proceed either incompletely or not at all in pyridine. This article reviews the various possible applications of 4-dialkylaminopyridines in terpene, steroid, carbohydrate and nucleoside chemistry as well as in the transformation of amino acids into α-acyl aminoketones and polymerization of isocyanates. In addition, N-substituted 4-dialkylaminopyridinium salts can be used for the transfer of sensitive groups to nucleophiles in aqueous medium. The exceptional catalytic effect of these derivatives, even in non-polar solvents, is due, in part, to the formation of high concentrations of N-acylpyridinium salts which are present in solution as loosely-bound, highly reactive ion pairs.

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