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Synlett 2001; 2001(6): 0741-0744
DOI: 10.1055/s-2001-14608
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Solid-Phase Synthesis of Dihydropyrimidones via N-Acyliminium Ion-Based α-Ureidoalkylations

María García Valverde* , Doris Dallinger, C. Oliver Kappe
  • *Institute of Chemistry, Organic and Bioorganic Chemistry, Karl-Franzens-University Graz, Heinrichstraße 28, A-8010 Graz, Austria; Fax ++ 43-316-3 80 98 40; E-mail: oliver.kappe@uni-graz.at
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Publication Date:
31 December 2001 (online)

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The synthesis of 4-aryl-2-(thioxo)oxo-3,4-dihydropyrimidine-5-carboxylic acids is reported using two orthogonal solid-phase variations of the Biginelli condensation. In the first method, polymer-bound β-ketoesters are treated with aromatic aldehydes and urea under acidic conditions. The transient N-acyliminium ion that is initially formed from the aldehyde and urea precursors, is then intercepted by the resin-bound β-ketoesters. In an alternative approach, resin-bound β-ketoesters are condensed with aldehydes and O-methylisourea under basic conditions. Both orthogonal condensation procedures provide fair to excellent overall yields of the desired target structures.

synthetic methods - heterocycles - combinatorial chemistry - Biginelli reaction - solid-phase synthesis