Rapid PROTAC discovery platform: nanomole scale array synthesis and direct screening of reaction mixtures to facilitate the expedited discovery and follow-up of PROTAC hits.

Precise linker length, shape and linker attachment point are all integral components to designing efficacious PROTACs. Due to the increased synthetic complexity of these heterobifunctional degraders and the difficulty of computational modelling to aid PROTAC design, the exploration of structure-activity-relationship (SAR) remains mostly empirical, which requires a significant time and resource investment. To facilitate rapid hit finding we developed capabilities for PROTAC parallel synthesis and purification by harnessing an array of pre-formed E3-ligand linker intermediates. In the next iteration of this approach, we developed a rapid, nanomole-scale PROTAC synthesis methodology using amide coupling that enables direct screening of non-purified reaction mixtures in cell-based degradation assays, as well as logD and EPSA measurements. This approach greatly expands and accelerates PROTAC SAR exploration (5 days instead of several weeks) while using nanomole amounts of reagents. Lastly, it avoids laborious and solvent-demanding purification of the reaction mixtures, thus making it an economical and more sustainable methodology for PROTAC hit finding.