[N:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[C:7]1([CH2:12][OH:13])[CH2:11][CH2:10][CH2:9][CH2:8]1.C(N(CC)CC)C.[S:21](Cl)([CH3:24])(=[O:23])=[O:22].C(OCC)(=O)C>ClCCl.CCCCCC>[N:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]=1[C:7]1([CH2:12][O:13][S:21]([CH3:24])(=[O:23])=[O:22])[CH2:11][CH2:10][CH2:9][CH2:8]1To a stirred solution of (1-pyridin-2-yl-cyclopentyl)-methanol (432) (1.8 g, 10.169 mmol) in dichloromethane (20 mL), triethylamine (2.827 mL, 20.339 mmol) and mesylchloride (0.94 mL, 12.203 mmol) were added at 0° C. The reaction mixture was allowed to stir for 2 h at room temperature while silica thin layer chromatography was performed (50% ethyl acetate in hexane; Rf=0.6) The reaction was quenched with water (30 mL) and extracted with dichloromethane (2×70 mL). The organic part was dried and concentrated. The resulting crude product was purified by normal silica gel (100-200 mesh) column chromatography using 25% ethyl acetate in hexane as eluent to get methanesulfonic acid 1-pyridin-2-yl-cyclopentylmethyl ester (433) (2.05 g, 79%) as a white solid.
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