反应详情

Using the procedure of Example 20, 1.65 ml of dry pyridine and 1.33 ml of 2-chloro-aniline were added successively to a solution of 2.0 g of 3-methyl-1,2,4-oxadiazol-5-yl-acetic acid in a mixture of 13 ml of dioxane and 13 ml of toluene and the precipitation of a viscous oil was observed. The reaction mixture was stirred for 90 minutes at room temperature and then was evaporated to dryness. The residue was thoroughly stirred with 10 ml of iced water, whereupon dichloromethane was added. The pH of the resulting, clear two-layer system was 0.8 and the pH was raised to 3.0 and the layers separated. The water layer was extracted 4 times with 25 ml volumes of dichloromethane and the 5 extracts were combined, washed once with a small volume of iced water, dried over anhydrous magnesium sulfate, filtered and evaporated. The residue was crystallized from carbon tetrachloride to obtain 2.7 g (77% yield) of pure N-(2-chloro-phenyl)-3-methyl-1,2,4-oxadiazol-5-yl-acetamide with a m.p. of 118.5°-119.5° C.

1. customthe precipitation of a viscous oil
2. customwas evaporated to dryness
3. stirringThe residue was thoroughly stirred with 10 ml of iced water, whereupon dichloromethane
4. additionwas added
5. temperaturethe pH was raised to 3.0
6. customthe layers separated
7. extractionThe water layer was extracted 4 times with 25 ml volumes of dichloromethane
8. washwashed once with a small volume of iced water
9. dry with materialdried over anhydrous magnesium sulfate
10. filtrationfiltered
11. customevaporated
12. customThe residue was crystallized from carbon tetrachloride