Mixtures of dipeptide monomers create stereochemically and constitutionally complex dynamic libraries of potential receptors. When (−)-cytidine was utilized as guest an 84-membered cyclic host was amplified (70–175 fold) from a nearly undetectable initial concentration. Only the specified diastereomeric combination of the two chiral building blocks yielded a dynamic library from which the macrocyclic receptor could be amplified.