A two-step method for introducing a propargyl group in aromatic bioactive small molecules has been developed. This method features propargylation of aromatic groups using a cationic propargyl hexacarbonyl complex in the presence of cesium carbonate, and decomplexation of the resultant cobalt complexes using 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate. These reactions proceed under mild conditions, and thus are applicable for acid- and/or oxidant-sensitive aromatic bioactive small molecules.