反应详情

30.2 g of ethyl 3-dimethylaminoacrylate and 29.3 ml of triethylamine are dissolved in 180 ml of toluene and boiled at reflux. At this temperature a solution of 53 g of 4-bromo-2-chloro-benzoyl chloride (U.S. Pat. No. 4,959,363) in 50 ml of toluene is added dropwise over 30 min. and the mixture is subsequently heated at reflux for a further 1 hr. The mixture is left to cool to room temperature and is stirred in an ice bath for a further 30 min. The suspension is filtered and the precipitated triethylamine hydrochloride is washed with 40 ml of ice-cold toluene. The filtrate is concentrated to half of its volume and then, for crystallization, diluted with 100 ml of hexane and stirred in an ice bath for 1 hr. 51.2 g (67%) of ethyl 2-(4-bromo-2-chloro-benzoyl)-3-dimethylaminoacrylate are obtained as colourless crystals. M.p. 100°-101°.

1. temperatureat reflux
2. temperaturethe mixture is subsequently heated
3. temperatureat reflux for a further 1 hr
4. waitThe mixture is left
5. filtrationThe suspension is filtered
6. washthe precipitated triethylamine hydrochloride is washed with 40 ml of ice-cold toluene
7. concentrationThe filtrate is concentrated to half of its volume
8. customfor crystallization
9. additiondiluted with 100 ml of hexane
10. stirringstirred in an ice bath for 1 hr