To 0.14 g (0.43 mmol) (RS,SR)-2-benzenesulfonyl-2-(3-oxo-cyclohexyl)-propionic acid methyl ester in glacial acetic acid (3 mL), 88 mg (0.47 mmol, 1.1 eq) of (4-chloro-phenyl)-hydrazine hydrochloride were added and the reaction mixture was stirred at 40° C. over night. An aqueous solution of NaHCO3 was added until pH=7 was reached, and the mixture was extracted with EtOAc. The combined organic phases were dried over Na2SO4, filtered and evaporated. A column chromatography on silica gel with heptane/EtOAc 2:1 followed by a trituration with Et2O yielded 187 mg (65%) of (RS,SR)-2-benzenesulfonyl-2-(6-chloro-2,3,4,9-tetrahydro-1H-carbazol-2-yl)-propionic acid methyl ester as a white solid, MS: 432 (MH+).
