反应详情

After careful addition of absolute methanol (0.1 mL) to a suspension of sodium hydride (60% in mineral oil, 16 g, 0.40 mol) in anhydrous toluene (200 mL), a solution of 4-chloro-benzaldehyde (28 g, 0.20 mol) and 2-methyl-succinic acid dimethyl ester (48 g, 0.30 mol) in anhydrous toluene (100 mL) was added dropwise at room temperature under a stream of nitrogen. After being stirred at room temperature for 2 hours, the resulting mixture was diluted by adding 2 N sodium hydroxide (200 mL) dropwise, then heated to 80° C., and stirred at the same temperature for 2 hours. After being cooled to room temperature naturally, the aqueous layer was separated, washed with ethyl acetate (100 mL×3), then acidified with 2 N hydrochloric acid to pH 2, and extracted with ethyl acetate (150 mL×3). The combined organic layers were dried over sodium sulfate, and concentrated in vacuo. The residue was precipitated from ethyl acetate/petroleum ether (10:1) to give 2-(4-chloro-benzylidene)-3-methyl-succinic acid (13.4 g, 26%) as a yellow solid.

1. additionthe resulting mixture was diluted
2. temperatureheated to 80° C.
3. stirringstirred at the same temperature for 2 hours
4. temperatureAfter being cooled to room temperature naturally
5. customthe aqueous layer was separated
6. washwashed with ethyl acetate (100 mL×3)
7. extractionextracted with ethyl acetate (150 mL×3)
8. dry with materialThe combined organic layers were dried over sodium sulfate
9. concentrationconcentrated in vacuo
10. customThe residue was precipitated from ethyl acetate/petroleum ether (10:1)