Multiparameter exploration of piperazine derivatives as δ-opioid receptor agonists for CNS indications.

A novel series of piperazine derivatives exhibits sub-nanomolar binding and enhanced subtype selectivity as δ-opioid agonists. The synthesis and SAR are described as well as the application of computational models to improve in vitro ADME and safety properties suitable for CNS indications, specifically microsomal clearance, permeability, and hERG channel inhibition.