Cascade C-H Annulation Reaction of Benzaldehydes, Anilines, and Alkynes toward Dibenzo[ a, f]quinolizinium Salts: Discovery of Photostable Mitochondrial Trackers at the Nanomolar Level.

Fluorescent mitochondrial trackers with the dibenzo[ a, f]quinolizinium core are unprecedentedly synthesized by a one-pot protocol starting from commercially available benzaldehydes, anilines, and alkynes through a rhodium(III)-catalyzed cascade C-H N- and C-annulation reaction. Among them, 5g is the most prominent and exhibits high specificity, high efficiency at nanomolar level, superior photostability, and low cytotoxicity.