Used as a key chiral intermediate in the synthesis of pharmaceuticals, particularly in the production of serotonin-norepinephrine reuptake inhibitors (SNRIs) like duloxetine. Its enantiomeric purity is critical for achieving the desired biological activity in the final drug substance. Commonly employed in asymmetric synthesis routes where the ester functionality allows for further chemical modifications, such as hydrolysis or coupling reactions. Also utilized in the development of active pharmaceutical ingredients (APIs) requiring a phenylpropanamine backbone with specific stereochemistry.