反应详情

4.1 mmol of n-butyllithium (0.4 ml of 1.6 M solution in hexane) are added at -40° to a solution of 412 mg of diisopropylamine in 30 ml of dry tetrahydrofuran. After stirring for 30 minutes 672 mg of 2,5-dimethoxybenzyl-triphenylphosphonium bromide are added at this temperature. The suspension is stirred for another 30 minutes, cooled to -70° and treated with 300 mg of 2-acetylamino-5-formyl-benzoic acid methylester in 8 ml of absolute tetrahydrofuran. The mixture is stirred for one hour at -70° and for two hours at room temperature and then poured onto aqueous ammonium chloride solution. Extraction with ethyl acetate and evaporation yields a crude product, which is subjected to silica gel chromatography (hexane/ethyl acetate =9/1) to obtain the title compound as a mixture of the E- and Z-isomers.

1. additionare added at this temperature
2. temperaturecooled to -70°
3. stirringThe mixture is stirred for one hour at -70° and for two hours at room temperature
4. extractionExtraction
5. customwith ethyl acetate and evaporation
6. customyields a crude product, which