[C:1](=[O:4])([O-])[O-:2].[Na+].[Na+].[CH2:7]([O:11][C:12]1[CH:17]=[CH:16][C:15]([S:18](Cl)(=[O:20])=[O:19])=[CH:14][CH:13]=1)[C:8]#[C:9][CH3:10].Cl.C[N:24]([CH3:27])C=O>C(OCC)(=O)C.O>[CH2:7]([O:11][C:12]1[CH:17]=[CH:16][C:15]([S:18]([NH:24][C:27]2([C:1]([OH:2])=[O:4])[CH2:10][CH2:9][CH2:8][CH2:7]2)(=[O:20])=[O:19])=[CH:14][CH:13]=1)[C:8]#[C:9][CH3:10]To a solution of cis-2-amino-1-cyclopentane (1.0 g, 7.74 mmol) in 1:1 water:dimethylformamide (10 mL) at 0° C. was added sodium carbonate (2.7 g, 25.5 mmol) followed by 4-(2-butynyloxy)phenyl sulfonyl chloride (2.08 g, 8.5 mmol). The reaction mixture was allowed to warm to room temperature. After stirring overnight water and ethyl acetate were added and the mixture acidified to pH=1 with 6N aqueous hydrochloric acid. The organic phase was washed with water and brine and dried over anhydrous sodium sulfate. Filtration and concentration in vacuo gave (1R,2S)-2-[{[4-(2-butynyloxy)phenyl]sulfonyl}amino cyclopentanecarboxylic acid (1.58 g) as a white solid, mp 105-135° C. Electrospray Mass Spec 336.4 (M+H)+.
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