Mechanism-Driven Bioactive Indazole Frameworks: Photoinitiated Demethylation-Aromatization Synthesis and Biosensing...

Indazole frameworks are pivotal in medicinal chemistry and fluorescent conjugate design. Herein, we reported a photochemical strategy enabling efficient N-demethylation and aromatic cyclization of N-methyl amines via UV-induced nitroso intermediates, offering an environmentally benign route to structurally diverse 2H-indazole scaffolds. Diverging from conventional methods, this protocol demonstrates exceptional substrate compatibility with various alkyl/aryl amines, facilitating streamlined assembly of functionalized 2H-indazole modules. The methodology has been successfully applied to synthesize modified drugs and tumor-specific fluorescent probes targeting G-quadruplexes. Preliminary evaluations of physiological toxicity and cellular fluorescence imaging highlight their biomedical potential, establishing these strategies as potential tools for pharmacological development and bioimaging research.