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37. Synthesis of 1-Alkyl- and 1-Alkylidene Substituted 3-Oxo-carbo- and Heterocycles with Potential Biological Activity.
Stadlbauer W., Täubl A.E., Knobloch B.
Electronic Conference on Heterocyclic Chemistry, http://www.ch.ic.ac.uk/ectoc/echet98, June 29 - July 24, 1998

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 substuent 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