4-Fluoroindole (CAS number 387-43-9) is a mono-fluorinated indole, a benzene ring fused pyrrole heterocyclic compound. The derivatization of indole is versatile. Substitution of 1-position (on the nitrogen) is achieved with sodium hydride or potassium hydride making it a nucleophile. The 3-position can be activated with a Grignard reagent, namely methylmagnesium bromide or an organozinc compound. Position 2 of indole can be modified via directed ortho lithiation. After the expansion of chromophore, indole derivatives, triazatruxenes, are used as a donor unit in dye-sensitized solar cell with power conversion efficiency (PCE) of 13.6%.
Indole is an intercellular signal molecule; hence it is a promising pharmaceutical molecular scaffold for active pharmaceutical ingredients (APIs). 4F-Indole improves the effectiveness of kanamycin (an aminoglycoside antibiotic) against Pseudomonas aeruginosa, a multi-drug resistant pathogen.
Combining the photophysio-properties and bioactivity, 4-fluoroindole is use in bioimaging, for instance monitoring cancer cells under anti-cancer treatments.