This compound can be prepared by two related ways: 1) The diazotation of L-serine methyl ester (I) with NaNO2 - HCl gives methyl (S)-glycerate (II), which by reaction with 2,2-dimethoxypropane and p-toluenesulfonic acid (or acetone and ZnCl2) is converted to methyl (S)-O-isopropylideneglycerate (III). The reduction of (III) with LiAlH4 in refluxing ether affords (S)-2,3-O-isopropylideneglycerol (IV), which by reaction with tosyl chloride in pyridine is converted to the corresponding tosylate (V). The partial hydrolysis of (V) with HCl in acetone affords (S)-glycerol-1-tosylate (VI), which is finally condensed with 1-phenylpiperazine (VII) in refluxing benzene. 2) The partial hydrolysis of (S)-2,3-epoxypropyl tosylate (VIII) with HCl as before gives the glycerol tosylate (VI), already obtained.