反应详情

9 g of magnesium turnings are covered with 400 ml of dry tetrahydrofuran and the mixture is warmed to boiling. To that mixture is then added 2-(2',6'-dimethylphenyl)-1-bromoethane at such a rate that a gentle boiling is maintained. When the magnesium turnings have reacted the solution containing the Grignard reagent is cooled to room temperature. The reaction mixture is then added dropwise, over a period of 3 hours, to a cooled (0°-5° C.) solution of diethoxyacetic acid piperidinyl amide (80.8 g) in 200 ml of dry tetrahydrofuran. After the addition is complete, the reaction mixture is stirred for two hours at about 5° C. The mixture is then poured into a cold 2% sulfuric acid solution (1000 ml). The solution is extracted with toluene and the combined toluene extracts are washed with water and evaporated to dryness to give a residue of about 95 g. The residue is distilled under reduced pressure. The forefraction distilling below 120° C./0.6 mmHg is discarded and the rest, about 66 g, is crude 2-(2',6'-dimethylphenyl)-ethylglyoxal diethyl acetal, which is used without purification in step (b).

1. temperaturethe mixture is warmed to boiling
2. additionThe reaction mixture is then added dropwise, over a period of 3 hours
3. additionAfter the addition
4. extractionThe solution is extracted with toluene
5. washthe combined toluene extracts are washed with water
6. customevaporated to dryness
7. customto give a residue of about 95 g
8. distillationThe residue is distilled under reduced pressure
9. distillationThe forefraction distilling below 120° C./0.6 mmHg
10. customis used without purification in step (b)