[C:1]([O:5][C:6](=[O:15])[CH:7]([O:11][C:12](=[O:14])[CH3:13])[C:8]([CH3:10])=[O:9])([CH3:4])([CH3:3])[CH3:2].[H-].[Na+].[CH2:18](Br)[CH2:19][CH2:20][CH3:21]>CN(C=O)C>[C:1]([O:5][C:6](=[O:15])[C:7]([O:11][C:12](=[O:14])[CH3:13])([C:8](=[O:9])[CH3:10])[CH2:18][CH2:19][CH2:20][CH3:21])([CH3:2])([CH3:3])[CH3:4]According to the general alkylation method, tert-butyl-2-acetoxy-aceto-acetate (219a) (1.08 g, 5.00 mmol), NaH (156 mg, 6.5 mmol) and butylbromide (538 μL, 685 mg, 5.00 mmol) were reacted in DMF (10 mL) to give 2-acetoxy-2-acetyl-hexanoic-acid-tert-butylester (250i) (1026 mg, 3.77 mmol, 75%) as a slightly yellow oil. Then, 250i (731 mg, 2.68 mmol) and 51 mg (0.27 mmol) p-TsOH.H2O were stirred in 9.0 mL benzene according to decarboxylation method A. Kugelrohr distillation at 1.0 mbar and 60° C. gave 251i (415 mg, 2.41 mmol, 90%) as a colorless oil.
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