Ring-opening and cyclization of aziridines with aryl azides in the presence of TfOH has been developed. This strategy enables the construction of 6-(triflyloxy)quinoline cores by utilizing aziridine as a two-carbon surrogate. The introduction of a trifyl group at the 6-position of quinoline would allow further construction of carbon–carbon and carbon–heteroatom bonds in the cross-coupling reactions.