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Synfacts 2006(2): 0120-0120  
DOI: 10.1055/s-2005-924824
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart · New York

Multisubstituted Pyridines from 1,2,4-Triazines by Diels-Alder Chemistry

Contributor(s): Victor Snieckus, Robert Engqvist
Y. F. Sainz, S. A. Raw, R. J. K. Taylor*
University of York, UK
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Publication History

Publication Date:
23 January 2006 (online)

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Significance

Two methods for the preparation of multisubstituted pyridines, which involve Diels-­Alder reaction of 1,2,4-triazines with in situ generated enamines, are presented. The development of a solvent-free microwave-promoted procedure is a noteworthy feature of the enamine method. Pyrrolidine was shown to be the optimal secondary amine for the in situ-generated method while N-methylethylenediamine served as the best diamine for the tethered imine-enamine procedure. Both cyclic and acyclic ketones were shown to give highly substituted pyridines in reasonable to good yields.