[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][CH2:21][CH3:22]>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][CH2:21][CH3:22])([CH3:2])([CH3:3])[CH3:4]According to the general alkylation method, tert-butyl-2-acetoxy-aceto-acetate (219a) (7.12 g, 32.9 mmol), NaH (900 mg, 37.5 mmol) and pentylbromide (4.97 g, 32.9 mmol) were reacted in DMF (64 mL) to give 2-acetoxy-2-acetyl-heptanoic-acid-tert-butylester (250j) (6.40 g, 22.3 mmol, 68%) as a slightly yellow oil after Kugelrohr distillation at 185° C. and 1.0 mbar. Then, 250j (6.40 g, 22.3 mmol) and 402 mg (2.11 mmol) p-TsOH.H2O were stirred in 65 mL benzene according to decarboxylation method A. Kugelrohr distillation at 1.0 mbar and 125° C., followed by column chromatography (ethyl acetate:petroleum ether=1:4) gave 251j (1.6 g, 8.59 mmol, 39%) as a colorless oil.
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