• alkynylation
• imidazole

During this experimental Thesis, an effective strategy for the selective C-5 alkynylation of the imidazole ring was developed. A series of 5-alkynylimidazoles 73 was synthesized starting from 5-unsubstituted imidazoles 71 by employing a one-pot combination of a C-5 halogenation followed by a Sonogashira reaction. The developed strategy has been employed for the synthesis of imidazole-based chromophores end-capped with electron-donating (EDG) and electron-acceptor (EWG) groups ("push-pull” systems).
An efficient two-step procedure for the synthesis of symmetrically 4,5-disubstituted imidazoles (27) from 4,5-dibromoimidazole (74) was also developed, and some 2-aryl-4,5-bis(arylethynyl)imidazoles (79), which are potential “Y-shaped” chromophores, were prepared Their main fluorescence properties, such as absorption and emission maxima, Stoke’s shift and quantum yield were evaluated. Moreover, a new synthetic strategy involving a sequential C-5/C-4 double alkynylation of 4,5-dibromoimidazoles (74), concerning a site-selective Sonogashira reaction as the first step, was applied to the preparation of unsymmetrically substituted 4,5-dialkynylimidazoles 76, hardly obtainable from different pathways.