Modular Syntheses of Star‐Shaped Pyridine, Bipyridine, and Terpyridine Derivatives by Employing Sonogashira Reactions

Abstract

AbstractA simple and flexible synthesis for a series of star‐shaped pyridine, bipyridine, and terpyridine derivatives is reported by using a modular approach that combines the use of a ligand, spacer, and core unit. A fairly efficient method to prepare 4′‐nonafloxy‐functionalized terpyridine derivatives is described. The building blocks that contain the functionalized pyridine, bipyridine, or terpyridine derivatives were linked to different C3‐symmetrical core units. In most cases, Sonogashira reactions were employed in the crucial final steps of the synthesis. A star‐shaped dodecafluorinated compound was also prepared in a straightforward fashion. A simple procedure for the preparation of partially silylated 1,3,5‐triethynylbenzene derivatives is presented, which provides an approach to C2‐symmetrical star‐shaped compounds that have only one terpyridine and two terphenyl units as “dummy” ligands. The absorption and emission spectra of the fully conjugated C3‐symmetrical pyridine derivatives were systematically investigated, and fairly large Stokes shifts were observed.