C(Cl)(=O)C(Cl)=O.CS(C)=O.[CH2:11]([O:13][C:14]([C@H:16]1[CH2:21][CH2:20][C@H:19]([CH2:22][OH:23])[CH2:18][CH2:17]1)=[O:15])[CH3:12].C(N(CC)CC)C>ClCCl>[CH2:11]([O:13][C:14]([C@H:16]1[CH2:21][CH2:20][C@H:19]([CH:22]=[O:23])[CH2:18][CH2:17]1)=[O:15])[CH3:12]To a solution of oxalyl chloride (2.8 ml, 32 mmol) in dichloromethane (150 ml) was added dimethylsulfoxide (5.0 ml, 64 mmol) at −78° C. The mixture was stirred for 5 minutes at −50° C. A solution of cis/trans-4-hydroxymethyl-cyclohexanecarboxylic acid ethyl ester (3:1) (5.0 g, 27 mmol) in dichloromethane (30 ml) was added at −65° C. Stirring for 30 minutes was followed by addition of triethylamine (18.7 ml, 134 mmol). The cooling bath was removed 15 minutes after completed addition, and the reaction mixture was stirred for 2 h. The reaction mixture was concentrated to approximately 20-30 ml by rotating evaporation. The residue was partitioned between ethyl acetate (200 ml) and 0.5 M aqueous hydrochloric acid solution (100 ml). The layers were separated. The aqueous layer was extracted with one 100-portion of ethyl acetate. The combined organic layers were washed with one 100-ml portion of brine, dried over anhydrous sodium sulfate and concentrated in vacuo to give the title compound (4.9 g, 98%) as light yellow oil, which was used in the next step without further purification. MS m/e: 185 ([M+H]+)
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