反应详情

To a solution of 4-amino-3,5-diethoxy-benzoic acid ethyl ester (2.8 g, 11.05 mmol, 1.0 equiv; prepared as described in I. Kompis, A. Wick Helv. Chim. Acta 1977, 60, 3025-3034) in dichloromethane (50 mL) at 0° C. under Ar was slowly added diisobutylaluminium hydride (27.6 mL, 27.64 mmol, 2.5 equiv; 1.0 M solution in dichloromethane) over a time period of 15 min and the cooling bath removed on completion of addition. After stirring for 18 h, the excess hydride was quenched by cautious addition of a sat. solution of potassium sodium tartrate (10 mL). The solidified mixture was extracted with dichloromethane (5×200 mL) and THF (2×150 mL), the combined organic phases washed with water (3×100 mL), dried over MgSO4, concentrated by evaporation under reduced pressure and the crude material purified by column chromatography on silica eluting with a gradient of heptane/ethyl acetate (4:1→1:1) providing 1.10 g (47%) of the title compound. 1H NMR (300 MHz, CDCl3): δ 1.42 (t, J=7.0 Hz, 3H), 3.82 (br s, 2H), 4.05 (q, J=7.0 Hz, 2H), 4.54 (s, 2H), 6.50 (s, 2H). 13C NMR (75 MHz, CDCl3): δ 15.03, 64.21, 66.00, 104.51, 125.44, 129.89, 146.71. MS (ISP): 211.9 [M+H]+.

1. customprepared
2. customat 0° C.
3. customover a time period of 15 min
4. customthe cooling bath removed on completion of addition
5. customthe excess hydride was quenched by cautious addition of a sat. solution of potassium sodium tartrate (10 mL)
6. extractionThe solidified mixture was extracted with dichloromethane (5×200 mL) and THF (2×150 mL)
7. washthe combined organic phases washed with water (3×100 mL)
8. dry with materialdried over MgSO4
9. concentrationconcentrated by evaporation under reduced pressure
10. customthe crude material purified by column chromatography on silica eluting with a gradient of heptane/ethyl acetate (4:1→1:1)