In the present thesis nine new compounds (1a-c, 2a-c, 3a-c) were synthesized. The target structures of the type 3 are ring-A-modified derivatives of the alkaloid Luotonin A, which is due to its strong topoisomerase I inhibitory activity of pharmaceutical interest. The now available made 9,12, 10,12 and 11,12-disubstituted derivatives of the chemical lead should serve primarily to acquire new information about the structure-activity relationships in this class of antitumor-active compounds. For

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... he preparation of the intermediates 1a-c the Weinreb amidation was used. Ethyl 4-oxo-3,4-dihydroquinazoline-2-carboxylate and the corresponding 2,3, 2,4 and 2,5-dimethylated aniline were used through activation of the aniline nitrogen using the trimethylaluminum to synthesis N-(dimethylphenyl) - 4-oxo-3,4-dihydroquinazolin-2-carboxamide in very good yield. In the next step, the anilides of type 1 were selectively alkylated at N-3 with propargyl bromide / potassium carbonate in dimethylformamide. In the last step, the cyclization of the thus obtained N-propargyl compounds 2a-c was carried out to the target compounds 3a-c in an intramolecular [4 +2] - cycloaddition reaction at room temperature under the action of Hendrickson reagent. The latter is thereby produced in situ from triphenylphosphine and triflic anhydride.