is enantiomer of methyl (S)-phenyl[(S)-piperidin-2-yl]acetate A methyl phenyl(piperidin-2-yl)acetate in which both stereocentres have <i>S</i> configuration. It is the inactive enantiomer in the racemic drug methylphenidate. dexmethylphenidate methyl phenyl(piperidin-2-yl)acetate