反应详情

7 g of 1,3-dimethyl-7-(5-hydroxyhexyl)-xanthine and 9.5 g of p-toluene sulphonic acid are refluxed in 100 ml of toluene for 12 hours with continuous separation of the water formed in the reaction. After cooling to room temperature, the reaction mixture is mixed with 100 ml of diethyl ether, washed with sodium bicarbonate solution and water until neutral and the organic phase dried over sodium sulphate is evaporated under reduced pressure. After column chromatography on silica gel with methylene chloride/acetone (1:1) as eluent and distillation under reduced pressure a product is obtained from the residue which still contains a few percent of isomeric 1,3-dimethyl-7-(hex-5-enyl)-xanthine (as shown by the n.m.r. spectrum). Yield: 4.3 g (65.5% of theory relative to the starting product used). Melting point: 58°-64° C.

1. customformed in the reaction
2. washwashed with sodium bicarbonate solution and water until neutral and the organic phase
3. dry with materialdried over sodium sulphate
4. customis evaporated under reduced pressure
5. distillationAfter column chromatography on silica gel with methylene chloride/acetone (1:1) as eluent and distillation under reduced pressure a product
6. customis obtained from the residue which