反应详情

There were weighed out p-chlorophenyl-ethanol (5, racemic compound) (78 mg, 0.05 mmol) and (S)-(−)-3,3,5,5-tetramethyl-4H-dinaphtho[2,1-c:1′,2′-e]-azepin-N-oxyl (1.8 mg, 0.05 mmol). Then, 2 ml of acetone was added to obtain a uniform solution. Added thereto was 250 mg of silica gel (product of Merck, grade 9385) and the mixture was vigorously agitated for 5 minutes. The acetone used was distilled off under reduced pressure. Added thereto was 7% aqueous solution of sodium bicarbonate (5 ml) containing 20 wt. % of sodium bromide. Then, the mixture was thoroughly stirred. Two platinum electrodes (1.5×1.0 cm) were applied to the mixture which was then subjected to electrolytic oxidation reaction for 0.68 hour while being vigorously stirred at −15° C. and maintaining the current at 30 mA (quantity of electricity being 2.2 F/mol). After completion of reaction, silica gel was filtered off from the reaction mixture, extraction was effected with 5 ml of acetone and acetone was distilled off. The obtained residue was purified by silica gel column chromatography (ethyl acetate/hexane=7/1), giving p-chloroacetophenone (6) [39 mg, yield 100% based on the starting compound (5a)] and the starting compound (5b) (38 m, recovery percentage 97%, optical purity 83%).

1. customto obtain a uniform solution
2. additionAdded
3. distillationThe acetone used was distilled off under reduced pressure
4. additionAdded
5. additioncontaining 20 wt. % of sodium bromide
6. stirringThen, the mixture was thoroughly stirred
7. customwas then subjected to electrolytic oxidation reaction for 0.68 hour
8. stirringwhile being vigorously stirred at −15° C.
9. temperaturemaintaining the current at 30 mA (quantity of electricity being 2.2 F/mol)
10. customAfter completion of reaction, silica gel
11. filtrationwas filtered off from the reaction mixture, extraction
12. distillationwas distilled off
13. customThe obtained residue was purified by silica gel column chromatography (ethyl acetate/hexane=7/1)