Synthesis of π-extended CinNapht fluorophores via late-stage Pd-catalyzed C–N and C–C bond formation and application for selective imaging of lipid droplets in living cells

Abstract

We report the efficient synthesis of a 4′-brominated CinNapht scaffold, enabling late-stage functionalization via palladium-catalyzed cross-coupling reactions. This strategy granted access to 17 novel derivatives, including the first N-acetyl, N-carbamoyl, and N-aryl analogues, as well as entirely new C–C bonded structures via Suzuki–Miyaura, Heck, and Sonogashira couplings. These unprecedented modifications expand the π-conjugated system and tune the emission properties. Two of these fluorophores were successfully applied as selective probes for lipid droplet imaging in live cells, demonstrating the potential of this approach for biological sensing.