[CH3:1][C:2]1[O:3][C:4]([CH3:10])=[CH:5][C:6]=1[C:7]([OH:9])=[O:8].C(=O)([O-])[O-].[K+].[K+].[CH3:17][O:18][CH2:19][CH2:20][O:21][CH2:22]Cl>CN(C=O)C.O>[CH3:17][O:18][CH2:19][CH2:20][O:21][CH2:22][O:8][C:7]([C:6]1[CH:5]=[C:4]([CH3:10])[O:3][C:2]=1[CH3:1])=[O:9]A 2 L round-bottomed flask equipped with a mechanical stirrer was charged with 2,5-dimethyl-3-furoic acid (81.0 g, 0.58 mol) and potassium carbonate (95.9 g, 0.69 mol) in DMF (500 mL). An ice bath was used to cool the reaction as 2methoxyethoxymethyl chloride (72.2 g, 0.58 mol) was added portionwise. The reaction was stirred for 5 h at rt. The mixture was then diluted with water (1.5 L) and extracted with EtOAc (2×600 mL). The combined organics were washed with water (2×900 mL) and saturated sodium chloride solution (1 L), dried over MgSO4, filtered and concentrated to afford compound 803A (103 g, 82%) as a yellow oil. 1H NMR(CDCl3): δ=6.23 (s, 1H), 5.47 (s, 1H), 3.84 (m, 2H), 3.56 (m, 2H), 3.38 (s, 3H), 2.51 (s, 3H) and 2.20 ppm (s, 3H).
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