反应详情

To a stirred solution of 3-hydroxy-5-isopropoxy-benzoic acid methyl ester (3.76 g, 17.9 mmol) in THF (100 mL) at rt was added PPh3 (4.93 g, 18.8 mmol) and 2-(3-thienyl)ethanol (2.10 mL, 18.8 mmol). DIAD (3.71 mL, 18.8 mmol) was added dropwise at rt with external cooling to keep the solvent from boiling off. The resulting mixture was stirred at rt for 3 hr and concentrated to give a residue which was purified by silica gel chromatography (5×25 cm, hexane/EtOAc, v/v=10:1, 5:1). Fractions containing the product were pooled and concentrated to give 3-isopropoxy-5-(2-thiophen-3-yl-ethoxy)-benzoic acid methyl ester (5.24 g, 91%) as a yellow oil. 1H NMR (300 MHz, CDCl3): δ 7.28 (dd, J=5, 3 Hz, 1H), 7.15-7.18 (m, 2H), 7.08-7.09 (m, 1), 7.03 (dd, J=5, 1 Hz, 1H), 6.63 (m, 1H), 4.58 (m, 1H), 4.19 (t, J=7 Hz, 2H), 3.89 (s, 3H), 3.12 (t, 1=7 Hz, 2H), 1.33 (d, J=6 Hz, 6H).

1. temperaturewith external cooling
2. concentrationconcentrated
3. customto give a residue which
4. customwas purified by silica gel chromatography (5×25 cm, hexane/EtOAc, v/v=10:1, 5:1)
5. additionFractions containing the product
6. concentrationconcentrated