The complex of chiral C2-symmetric bis-1,2,3-triazole and an achiral Bronsted acid is introduced as a new class of chiralacid catalysts. The catalytic activity and stereocontrolling ability of this chiral Bronsted acid can be tuned simply by changing the achiral acid. The synthetic relevance of this salient feature is demonstrated in the asymmetricFriedel–Craftsreaction of indoles with N-sulfonyl