Sulfolane Mediated Highly Selective Synthesis of Mono and Bis-aryl-2-Methyl-6- Fluoro-Indoles and Their Halogenated Synthons

A simple, efficient, and cheap strategy has been developed for N-arylation of indoles with hexafloro benzene (1) via incorporating sulfolane as an eco-friendly solvent. NMonopentafluoroarylindole (3) at ambient conditions and N, N-bistetrafluoroaryl indole (4) at elevated temperatures were conveniently obtained by simple nucleophilic substitution using NaOH as the base and sulfolane as a reaction medium to obtain in moderately good yields, respectively. Subsequently, 3-chloro, 3-bromo, and 3-iodomono-pentafluoroarylindoles and 3, 3’-dichloro, 3, 3’-dibromo and 3, 3’-diIodobistetrafluoroaryl indoles were prepared in good yields by using respective halogenating reagents and solvents. All the chemical transformations were confirmed by analytical tools such as 1HNMR, FR-IR and HRMS analysis.