Detection of Lysosome by a Fluorescent Heterocycle: Development of Fused Pyrido-Imidazo-Indole Framework via Cu-Catalyzed Tandem N-Arylation.

Fluorescent active small molecules for organelle-specific bioimaging are in great demand. We synthesized 20 different pyrido-imidazo-indole fused heterocycles (6-5-5-6 ring) via copper catalyzed tandem N-arylation reaction in moderate to good yields. Due to decent fluorescent property, lysosome-directing moieties were attached on two of these heterocycles. Delightfully, those molecules tracked lysosome with bright blue fluorescence and colocalized with a known lysosome marker (Lysotracker Red) in human/murine cells. Therefore, it may be considered as a rapid (10 min) lysosome staining probe.