[N:1]1[CH:6]=[CH:5][N:4]=[CH:3][C:2]=1[C:7]([OH:9])=O.[C:10]([O:14][C:15](=[O:25])[CH2:16][C:17]1[CH:22]=[CH:21][C:20]([O:23][CH3:24])=[CH:19][CH:18]=1)([CH3:13])([CH3:12])[CH3:11].[H-].[Na+].O>CN(C)C=O.C(O)(=O)C>[C:10]([O:14][C:15](=[O:25])[CH:16]([C:17]1[CH:18]=[CH:19][C:20]([O:23][CH3:24])=[CH:21][CH:22]=1)[C:7](=[O:9])[C:2]1[CH:3]=[N:4][CH:5]=[CH:6][N:1]=1)([CH3:12])([CH3:13])[CH3:11]N,N-Carbonylimidazole (14.86 g) was added to a slurry of pyrazine-2-carboxylic acid in dry dimethylformamide (100 cm3). After stirring for one hour 4-methoxyphenylacetic acid t-butyl ester (10.8 g) was added. The reaction mixture was cooled to −30° C. then sodium hydride (4.62 g) was added. The reaction mixture was stirred at −30° C. for 1 h then allowed to warm to room temperature overnight. The reaction miLture was poured into water and acidified to pH 8 with acetic acid. The solution was extracted with ether (3×250 cm3). The ether extracts were combined, washed with brine, dried over magnesium sulphate filtered and evaporated under reduced pressure to give a solid. The solid was purified by chromatography using ethyl acetate/hexane (1:1) as eluant. The appropriate fractions were combined and evaporated under reduced pressure to give 2-(4-methoxyphenyl)-3-oxo-3-pyrazine-2-yl propionic acid t-butyl ester as a solid (9.8 g 61%) δH (250 MHz; CDCl3) 1.39 (9 H, s, C(CH3)3), 3.70 (3 H, s, OCH3), 5.87(1 H, s, tBuO2CCH), 6.90 (2H, d, J 9 Hz, methoxyphenyl H-2) 7.32 (2H, d, J 9 Hz, methoxyphenyl H-3) 8.66 (1H, dd pyrazine H—) 8.74 (1H, d pyrazine H—) 9.25 (1H, d pyrazine H—)
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