Multiple Sonogashira Reactions of Polychlorinated Molecules. Synthesis and Photophysical Properties of the First Pentaalkynylpyridines

Hitherto unknown pentaalkynylpyridines have been prepared in high yields by Sonogashira cross-coupling reactions of pentachloropyridine. Their photophysical properties were studied and compared to those of penta- and hexaalkynylbenzenes which were efficiently prepared by the first Sonogashira reactions of pentachlorobenzene and hexachlorobenzene. The pentaalkynylpyridines show promising fluorescence properties because of their high quantum yields.