(2R,3S)-E1R (Compound 2c) is an enantiomer of E1R. (2R,3S)-E1R is a sigma-1 receptor positive allosteric modulator (Sig1R PAM) for the treatment of cognition/memory disorders.In Vitro: Sigma-1 receptor plays an important role in neuronal plasticity, a process implicated in the pathophysiology of neuropsychiatric diseases, such as Alzheimer’s disease, major depressive disorders, and schizophrenia.