反应详情

Firstly, the starting compound N,N-dibutyl-4-amino-2-hydroxy-benzaldehyde had to be prepared by Vilsmeyer formylation of N,N-dibutyl-3-amino-phenol. The Vilsmeyer reagent was prepared by slow addition of 4.7 ml (0.0497 mol) of phosphorus oxychloride to 15 ml (0.189 mol) of N,N-dimethyl formamide with stirring for 15 minutes at room temperature. Stirring was continued for 30 more minutes before this Vilsmeyer reagent was used. 11 g (0.497 mol) N,N-dibutyl-3-amino-phenol, prepared by alkylation of 3-aminophenol after the procedure described in EP 0356173 was dissolved in 13 ml N,N-dimethyl formamide. This solution was added dropwise at room temperature to the Vilsmeyer reagent described above. The solution was stirred for 3 h, heated to 50° C. for 10 minutes. The solution was cooled to room temperature and stirred for another 2 h. Then, the reaction mixture was poured onto 70 g ice and stirred for 1 h. The aequous layer was extracted three times with 100 ml chloroform. The combined organic layers were evaporated in vacuo. The raw product was purified by column chromatography (450 g silicagel, eluent hexane/ethyl acetate 15:1, vol. ratio). 3.2 g (26%) N,N-Dibutylamino-2-hydroxy-benzaldehyde was obtained as an orange oily compound.

1. stirringStirring
2. additionThis solution was added dropwise at room temperature to the Vilsmeyer reagent
3. stirringThe solution was stirred for 3 h
4. temperatureheated to 50° C. for 10 minutes
5. temperatureThe solution was cooled to room temperature
6. stirringstirred for another 2 h
7. stirringstirred for 1 h
8. extractionThe aequous layer was extracted three times with 100 ml chloroform
9. customThe combined organic layers were evaporated in vacuo
10. customThe raw product was purified by column chromatography (450 g silicagel, eluent hexane/ethyl acetate 15:1, vol. ratio)