An extensive study of the chemoselective Pd-catalyzed inter- and intramolecular direct C–H arylation of N-benzylated 5-carboxyimidazoles with halides with and without CuI assistance in 1,4-dioxane as a low-polarity solvent was explored. The method was suitable for the synthesis of fused imidazole-based tricyclic systems incorporating medium-sized rings, including, for the first time, eight-membered rings, which are valuable in modern drug design.

An original design and synthesis of fluorescent ligands for melatonin receptor studies is presented and consists in the fusion of the endogenous ligand with the fluorescent BODIPY core. Probes I-IV show high affinities for MT1 and MT2 melatonin receptors and exhibit fluorescence properties compatible with cell observation.