[CH2:1]([S:3]([CH2:6][CH2:7][C:8]12[CH2:15][CH2:14][C:11]([C:16]([OH:18])=O)([CH2:12][CH2:13]1)[CH2:10][CH2:9]2)(=[O:5])=[O:4])[CH3:2].[C:19](Cl)(=O)[C:20](Cl)=O.C[N:26]([CH:28]=O)C>C(Cl)Cl>[CH:20]12[CH2:19][CH:10]3[CH2:9][CH:8]([CH2:13][CH:12]([CH2:11]3)[CH:28]1[NH:26][C:16]([C:11]13[CH2:10][CH2:9][C:8]([CH2:7][CH2:6][S:3]([CH2:1][CH3:2])(=[O:5])=[O:4])([CH2:15][CH2:14]1)[CH2:13][CH2:12]3)=[O:18])[CH2:7]2Carboxylic acid 1-4 (810 mg, 3 mmol) was dissolved in methylene chloride (5 ml) and treated with oxalyl chloride (4 eq.) and 0.050 ml of DMF. The reaction was stirred at room temperature for 45 min, then the solvent was removed under reduced pressure to give a quantitative crude yield of 4-[2-(ethylsulfonyl)ethyl]bicyclo[2.2.2]octane-1-carboxyl chloride (1-5).
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