An approach to the design of novel cognitive enhancers using molecular modeling and X-ray crystallography

A novel series of cognition enhancers was designed based on molecular modeling and X-ray structure analysis of EXP-9121 (2). This new series features a spirocyclic ring system that constrains the side chain substituents into the orientation seen in the X-ray crystal structure of 2. MM2 calculations preformed on 2 accurately predicted the solid state conformation. Compounds could be rapidly assembled using a bis-Michael addition reaction. Unfortunately, in vitro testing showed moderate activity at best, suggesting the X-ray structure of 2 does not mimic the bioactive conformation.