[C:1]([O:5][C:6]([CH:8]1[CH2:12][CH2:11][CH:10]([OH:13])[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[CH3:14][S:15](Cl)(=[O:17])=[O:16].C(N(CC)CC)C>ClCCl>[C:1]([O:5][C:6]([CH:8]1[CH2:12][CH2:11][CH:10]([O:13][S:15]([CH3:14])(=[O:17])=[O:16])[CH2:9]1)=[O:7])([CH3:4])([CH3:2])[CH3:3]To a cold (−20° C.) solution of Rac-(1S,3R)-3-Hydroxy-cyclopentanecarboxylic acid tert-butyl ester (0.905 g) in dichloromethane (12 mL) was added methanesulfonylchloride (0.664 g) and triethylamine (0.636 g). The reaction mixture was stirred 10 min at −20° C. then poured into ice-water. Organic layer was washed with brine and dried over sodium sulfate then concentrated in vacuo to afford the title compound (1.15 g, 89%) as light yellow oil, used without further purification in the next step. MS (EI): 282 (M+NH4)+.
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