反应详情

7.0 g (55 mmol) of oxalyl chloride are introduced into 18.5 g (50 mmol) of 5-hydroxy-2,2,6,6-tetramethyl-4-(2-methyl-6-trifluoromethylpyridine-3-carbonyl)cyclohex-4-ene-1,3-dione (compound A2-B354), dissolved in 50 ml of dichloromethane; 5 drops of dimethylformamide are added, and the mixture is slowly heated up to boiling point. After approximately 30 minutes, after the evolution of gas has ceased, the mixture is evaporated and the product is crystallized by adding n-hexane. The main product obtained is pure 5-chloro-2,2,6,6-tetramethyl-4-(2-methyl-6-trifluoromethylpyridine3-carbonyl)cyclohex-4-ene-1,3dione, m.p. 119.5-120° C. Further HPLC-separation of the mother liquor using 5-10% ethyl acetate in hexane gives the isomer 6-[chloro-(2-methyl-6-trifluoromethylpyridine-3-yl)methylene]-2,2,4,4-tetramethylcyclohexane-1,3,5-trione, m.p. 92.5-93° C.

1. temperaturethe mixture is slowly heated up
2. customthe mixture is evaporated
3. customthe product is crystallized
4. additionby adding n-hexane
5. customThe main product obtained