Rapid Elaboration of Fragments into Leads by X‑ray Crystallographic Screening of Parallel Chemical Libraries (REFiL_X)

A bottleneck in fragment-based lead development is the lack of systematic approaches to elaborate the initial fragment hits, which usually bind with low affinity to their target. Herein, we describe an analysis using X-ray crystallography of a diverse library of compounds prepared using microscale parallel synthesis. This approach yielded an 8-fold increase in affinity and detailed structural information for the resulting complex, providing an efficient and broadly applicable approach to early fragment development.