[Mg].BrC(Br)C.[CH2:6]([C:8]1[CH:13]=[C:12]([CH3:14])[CH:11]=[C:10]([CH2:15][CH3:16])[C:9]=1Br)[CH3:7].[C:18](OCC)(=[O:24])[C:19]([O:21][CH2:22][CH3:23])=[O:20].Cl>O1CCCC1>[CH2:6]([C:8]1[CH:13]=[C:12]([CH3:14])[CH:11]=[C:10]([CH2:15][CH3:16])[C:9]=1[C:18](=[O:24])[C:19]([O:21][CH2:22][CH3:23])=[O:20])[CH3:7]To a 3 L volume four-necked flask, magnesium (turnings, 35.31 g), tetrahydrofuran (anhydrous, 600 ml) were added under nitrogen atmosphere at room temperature. After the stirring was started, the mixture was heated to about 30° C. of the internal temperature, and then dibromoethane (25.4 g) was added dropwise over 20 minutes. The resulting mixture was stirred for 30 minutes, and heated to about 50° C. of the internal temperature. To the mixture was added a solution of 2,6-diethyl-4-methylbromobenzene (300.18 g) in tetrahydrofuran (150 ml) dropwise over 2 hours. The resulting mixture was stirred at 50° C. for 1 hour, and then diethyl oxalate (192.5 g) was added dropwise at about 0° C. over 15 minutes. The resulting mixture was stirred at room temperature for 2 hours. To the mixture was added 3.5 weight % of hydrochloric acid (1000 ml) and concentrated hydrochloric acid (60 ml) with cooling. Then, the organic layer was evaporated, and the aqueous layer was extracted with tert-butyl methyl ether. The organic layer was concentrated under reduced pressure to give 320.82 g of ethyl (2,6-diethyl-4-methylphenyl)glyoxylate.
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