Development of a chiral macrocycle for the synthesis of mechanically planar chiral rotaxanes. The AT-CuAAC reaction with small bipyridine macrocycles is thought to proceed by formation of a mono-metallic Cu I -acetylide-azide complex 20 in which the metal ion is coordinated by the bipyridine unit of the macrocycle such that the azide and acetylide ligands are projected on opposite sides of the ring. This complex then reacts to generate a threaded Cu I -triazolide 20a before protonolysis of the Cu-C bond to generate the triazole product. Based on this mechanistic hypothesis, bipyridine macrocycle (S)-1a (Figure ) was designed and synthesized in which the chiral unit (>99% ee), derived from (S)-phenyl alanine methyl ester, is adjacent to the bipyridine moiety in the hope of maximizing the stereodifferentiation in the key bond forming step.