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74. Synthesis of 1-Alkyl- and 1-Alkylidene Substituted 3-Oxo-carbo- and Heterocycles with Potential Biological Activity
Stadlbauer W., Täubl A. E., Knobloch B., Proceedings of the Electronic Conference on Heterocyclic Chemistry '98 (ECHET98), H. S. Rzepa and C. O. Kappe, (Eds), Imperial College Press, 1998; CD-ROM, ISBN 981-02-3594-1, paper 18.

Abstract: In this communication some new synthetic pathways to pharmacologically interesting target molecules are described. Carbo- and heterocyclic 1,3-dioxo compounds 1 having as basic ring system a pyridine, pyrane, quinoline, coumarin or phenalenone nucleus, give the reactive 1-chloro-3-oxo intermediates 2, which can be alkylated with CH-acidic compounds such as malonates if the substituent R1 has electron acceptor properties . Alkyl derivatives 3 have been shown in some cases (e.g. as 4-alkyl-2-pyridones) to possess antiviral activity .
The thermolytic degradation of ethyl malonates of type 3 gives the ethyl acetates 4. With the 2-quinolone ring system this class of compounds shows manifold pharmacological activities.
Methyl malonates 3 having as substituent R1 a nitro group form under thermolytic conditions by loss of carbon dioxide and methanol isoxazoles of type 7. The thermolysis reactions to 4 and 7 have been studied by differential scanning calorimetry (DSC).
The Wittig- or Grignard reaction of 2,2-disubstituted 1,3-dicarbonyl carbo- or heterocycles 5 with alkyl-triphenylphosphonium halides leads to 1-alkylidene-3-oxo compounds 6. This compound class was recently found to show antiviral activities .

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abstract scheme