Potassium Carbonate → Ethyl 2-ethyl-4-hydroxy-1-benzofuran-6-carboxylate
反応式
C([O:4][C:5]1[C:10]2[CH:11]=[C:12]([CH2:14][CH3:15])[O:13][C:9]=2[CH:8]=[C:7]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[CH:6]=1)(=O)C.C([O-])([O-])=O.[K+].[K+]>C(O)C>[CH2:14]([C:12]1[O:13][C:9]2[CH:8]=[C:7]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[CH:6]=[C:5]([OH:4])[C:10]=2[CH:11]=1)[CH3:15]参加物
4
実験手順
A suspension of ethyl 4-(acetyloxy)-2-ethyl-1-benzofuran-6-carboxylate (8.0 g, 29.0 mmol) and K2CO3 (4.81 g, 34.8 mmol) in ethanol (80 mL) was refluxed for 24 hours. TLC (petroleum ether/EtOAc 4:1) showed complete consumption of the acetate. The solvent was removed under reduced pressure and the residue was poured into water (30 mL). The aqueous phase was acidified to pH˜2 with 10% aqueous HCl (50 mL) and extracted with EtOAc (100 mL×2). The organic layer was dried over Na2SO4 and concentrated. The residue was purified by column chromatography on silica gel eluted with petroleum ether/EtOAc (40:1) to afford the desired compound (6.0 g, 88%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.87 (s, 1H), 7.45 (s, 1H), 6.46 (s, 1H), 6.36 (s, 1H), 4.34-4.27 (q, 2H), 2.77-2.71 (q, 2H), 1.40-1.31 (t, 3H), 1.31-1.21 (t, 3H).