反应详情

Concentrated sulphuric acid (0.5 ml) was added to a stirred solution of 2-hydroxy-5-(2-methoxyethoxy)benzoic acid (2 g) in ethanol (50 ml). The mixture was heated at reflux for 12 hours. The reaction mixture was added to sodium hydrogen carbonate solution (5% by weight in water, 200 ml) and the aqueous mixture was extracted with ethyl acetate (4×50 ml). The organic extracts were combined, washed with water (50 ml), brine, (50 ml), dried (MgSO4) and evaporated to give 2-ethoxycarbonyl-4-(2-methoxyethoxy)phenol (1.85 g) as an oil; NMR: 1.35(3H,t), 3.31(3H,s), 3.6(2H,m), 4.0(2H,m), 4.3(2H,q), 6.9(1H,d), 7.18(1H d of d), 7.2(1H,d); m/z 241(MH). This was converted into the trifluoromethane sulphonate ester using an analogous procedure to that described in Example 1 for the preparation of ethyl 3-(3-allyl-4-trifluoromethylsulphonyloxy)propionate. There was thus obtained after chromatography on silica gel (Varian bond elut S1 silica gel) using a gradient of 5 to 25% ethyl acetate in hexane as eluent as an oil; NMR(6): 1.3(3H,t), 3.3(3H,s), 3.62(2H,m), 4.2(2H,m), 4.34(2H,q), 7.35(1H, d of d), 7.49(2H,m); m/z 373(M+H).

1. temperatureThe mixture was heated
2. temperatureat reflux for 12 hours
3. extractionthe aqueous mixture was extracted with ethyl acetate (4×50 ml)
4. washwashed with water (50 ml), brine, (50 ml)
5. dry with materialdried (MgSO4)
6. customevaporated