Naphthyridine Based Molecular Switches

Abstract: This thesis is focused on the synthesis and halogenation of 1,5-naphthyridine and 2,6-naphthyridine with the aim of finding a suitable method to synthesize mono- and bis-naphthyridine centered tridentate ligands for ruthenium complexes. Firstly the halogenated naphthyridines were synthesized, then 2-(2-thienyl)-6-ributylstannylpyridine was synthesized, and the two building blocks were coupled through a Stille cross coupling reaction. The thesis describes the synthesis of 2,6-dichloro-1,5-naphthyridine, 2-chloro-1,5-naphthyridine, 1,5-dichloro-2,6-naphthyridine and 1-chloro-2,6-naphthyridine. The synthesis of many of the halogenated naphthyridines have previously been reported, with the exception of 1,5-dichloro-2,6-naphthyridine and some of its intermediates which, at present, to the best of the authors knowledge , has not been reported. Three strategies have been successfully tested for the synthesis of 1,5-dichloro-2,6- naphthyridine. Secondly the thesis describes the synthesis of 2-(2-thienyl)-6-tributylstannylpyridine. The method of choice for synthesizing this Stille reagent was a Negishi coupling between 2-bromo-6- tributylstannylpyridine and 2-thiophenyl zinc chloride. Thirdly the thesis describes a method for the synthesis of bis-2,6-(2-(2-thienyl)6-pyridinyl)-1,5-naphthyridine through a Stille cross-coupling