(R)-(2S)-9-Hydroxy Risperidone-(O-chroman-2-carboxylate)-d4 is an intermediate used in the synthesis of (S)-9-Hydroxy Risperidone-d4 (H953362), which is the S-enantiomer metabolite of Risperidone (R525000), a combined serotonin (5-HT2) and dopamine (D2) receptor antagonist.