[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)[CH3:19]>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][CH3:19])([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 ethylbromide (also propyl and pentyl) (373 μL, 549 mg, 5.00 mmol) were reacted in DMF (10 mL) to give 2-acetoxy-2-acetylbutanoic-acid-tert-butylester (250g) (970 mg, 3.97 mmol, 79%) as a slightly yellow oil. Then, 250 g (1.40 g, 5.73 mmol) and 109 mg (0.57 mmol) p-TsOH.H2O were stirred in 18.0 mL benzene according to decarboxylation method A. Kugelrohr distillation gave 486 mg (3.4 mmol, 59%) of 251 g as a colorless oil.
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