Decarboxylative Fluorination of Electron-Rich Heteroaromatic Carboxylic Acids with Selectfluor.

A transition-metal-free decarboxylative fluorination of electron-rich five-membered heteroaromatics, including furan-, pyrazole-, isoxazole-, thiophene-, indole-, benzofuran- and indazolecarboxylic acids, with Selectfluor is reported. Fluorinated dimer products were observed for nitrogen-containing heteroaromatic carboxylic acids, such as indole and pyrazole. An effective method has been developed to synthesize the monomer of 2- and 3-fluoroindoles with Li2CO3 as base at low temperature.