反应详情

48.4 g of ethyl 2-chloro-5-ureido-benzoate and 31.2 g of ethyl cyclopentanone-2-carboxylate are heated under reflux for 6 hours in 500 ml of benzene and 2 g of toluene-4-sulphonic acid monohydrate. The water formed is removed by means of a water separator. The reaction mixture is subsequently evaporated to dryness, the residue is dissolved in 700 ml of diethyl ether and the solution is filtered. The filtrate is evaporated to dryness and the residue is purified by chromatography on 1.5 g of silica gel using diethyl ether/n-hexane (1:2) as the eluent. There is obtained ethyl 2-chloro-5-{3-[2-(ethoxycarbonyl)-1-cyclopenten-1-yl]ureido}-benzoate as colourless crystals. The product is recrystallized from diethyl ether/n-hexane, m.p. 110°-112° C.

1. customis removed by means of a water separator
2. customThe reaction mixture is subsequently evaporated to dryness
3. dissolutionthe residue is dissolved in 700 ml of diethyl ether
4. filtrationthe solution is filtered
5. customThe filtrate is evaporated to dryness
6. customthe residue is purified by chromatography on 1.5 g of silica gel