A Green N-Detosylation of Indoles and Related Heterocycles Using Phase Transfer Catalysis

A practical method for the N-detosylation of indoles and related heterocycles with KOH in THF and water in the presence of a phase transfer catalyst is described. Using a nonalcoholic solvent, this method prevents the formation of toxic alkyl p-toluenesulfonate and consequently eliminates the formation of even traces of N-alkyl byproduct. This green method is particularly useful for indoles bearing electron-withdrawing groups and for azaindoles.