Switchable cascade C–H annulation to polycyclic pyryliums and pyridiniums: discovering mitochondria-targeting fluorescent probes

Abstract

Disclosed herein is a counterion additive-switched rhodium-catalyzed cascade triple C–H annulation of 4-hydroxy-1-naphthaldehydes with alkynes, in which six chemical bonds are formed in one-pot. This reaction enables the rapid assembly of diverse polycyclic pyrylium and pyridinium fluorophores, which leads to two specific mitochondria-labeling reagents with low cytotoxicity and superior photostability.