The discovery of new compounds for the pharmacological manipulation of protein function often embraces the screening of compound collections, and it is widely recognized that natural products offer beneficial characteristics as protein ligands. Much effort has therefore been focused on 'natural product-like' libraries, yet the synthesis and screening of such libraries is often limited by one or more of the following: modest library sizes and structural diversity, conformational heterogeneity and the costs associated with the substantial infrastructure of modern high-throughput screening centres. Here, we describe the design and execution of an approach to this broad problem by merging principles associated with biologically inspired oligomerization and the structure of polyketide-derived natural products. A novel class of chiral and conformationally constrained oligomers is described (termed 'chiral oligomers of pentenoic amides', COPA), which offers compatibility with split-and-pool methods and can be screened en masse in a batch mode. We demonstrate that a COPA library containing 160,000 compounds is a useful source of novel protein ligands by identifying a non-covalent synthetic ligand to the DNA-binding domain of the p53 transcription factor.