In this master's thesis, we first synthesized seven 3-benzamido-substituted
pyrido[1,2-a]pyrimidinones, quinolizinones, and pyrimido[1,2-b]pyrazinones. In the next step, N-(1-cyano-4-oxo-4H-quinolizin-3-yl)benzamide and N-(4-oxo-4H-pyrido[1,2-a]pyrimidin-3-yl)benzamide were hydrolyzed and the obtained amines were converted into the corresponding azides via nitrosation. Next, copper-catalyzed cycloadditions of title azides to terminal alkynes and a strain-promoted cycloaddition to a cyclooctyne derivative were studied. Ten novel compounds were synthesized using these two cycloaddition reactions under optimized conditions. All novel compounds were characterized in terms of their structure and optical properties. Photochemical reactions of 3-azido-4H-pyrido[1,2-a]pyrimidin-4-one were also performed, however, only the formation of a product formed in the reaction of azide with tetrahydrofuran could be determined. We also proposed a new, more adequate and experimentally supported mechanism of thermal transformation of title azides. The proposed mechanism of thermal transformation is also amenable to photochemical reactions, as nitrene is most likely formed as a central intermediate regardless of the mode of activation (thermal or photochemical). Finally, by reacting 3-benzamido-9-propargyloxy-4H-pyrido[1,2-a]pyrimidin-4-one with 1,2-bis(2-azidoethoxy)ethane, the corresponding bis-cycloadduct was synthesized as a precursor of a homobifunctional fluorescent marker.
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