(+) or (−)-tert-butyl 3-(3-hydroxyphenyl)piperazine-1-carboxylate (tr=9.7 min) (Biological Example 2.1) (300 mg, 1.078 mmol) and benzyl 2-hydroxyethylcarbamate (210 mg, 1.078 mmol) were dissolved in THF (10 ml). Tributylphosphine (0.404 ml, 1.617 mmol) was added, and after cooling to 0° C., DEAD 40% in toluene (0.640 ml, 1.617 mmol) was added dropwise. The reaction was stirred for 2 h at 0° C., then overnight at rt. The reaction mixture was diluted with aqueous NaHCO3. The layers were separated and the aqueous layer was extracted with AcOEt. The organic phase dried over MgSO4 and concentrated in vacuum. The crude residue was purified by preparative HPLC (Macherey-Nagel Nucleosil 100-10 C18, CH3CN/H2O (0.1% TFA)) to give the title compound. MS (ESI+) m/z 455.2 (M+H).
