C[C:2]1([C:10]([OH:12])=[O:11])[CH2:7][CH2:6][C:5]([CH3:9])([CH3:8])[CH2:4][CH2:3]1.[CH:13](NC(C)C)(C)C.[Li].[CH3:21][O:22][C:23](Cl)=[O:24]>C1COCC1>[CH3:8][C:5]1([CH3:9])[CH2:6][CH2:7][C:2]([C:10]([O:12][CH3:13])=[O:11])([C:23]([O:22][CH3:21])=[O:24])[CH2:3][CH2:4]1A solution of methyl 4,4-dimethyl-cyclohexane carboxylic acid (7.17 g, 42.2 mmol) in THF (15 mL) was added dropwise to a solution of lithium diisopropylamine (6.84 g, 63.3 mmol) in THF (60 mL) at −78° C. After stirring for 1 h at the same temperature, a solution of methylchloroformate (6.0 g, 63.3 nmol) in THF (15 mL) was added slowly and the mixture was allowed to warm to room temperature. After 18 h the reaction mixture was quenched with saturated aqueous NH4Cl solution (150 mL) and the aqueous residue was extracted with EtOAc (100 mL×5). The combined organic layers were dried (MgSO4). After removal of the solvent under reduced pressure, purification by flash column chromatography using an eluting system of hexane/EtOAc (95:5) yielded the title compound as a clear colorless liquid (5.23 g, 54%). MH+229.
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