反应详情

Sodiomethylacetoacetate was prepared by adding an excess of methylacetoacetate (74.3 g, 0.64 mole) to a solution of sodium ethoxide (31.3 g, 0.46 mole) in 150 mls. absolute ethanol at 25°. The reaction mixture was cooled to 0° and then the crude chloride prepared above was added dropwise over a 25-minute period and stirring was continued at 0° for an additional 3 hours. After this period, the temperature was allowed to rise to ambient over a 40-minute period. A portion of the ethanol (78.0 g) was distilled at this point by stirring the reaction mixture at 60°-65° for 2 hours under a slight vacuum. After cooling to 30°, 550 mls. of 10% aqueous NaOH was added over a 15-minute period and the reaction mixture was stirred at 70° for 4 hours. After settling, the layers were separated and the aqueous layer was saturated with NaCl and extracted with three 200-ml. portions of pentane. The combined oils were washed once with 1 liter H2O and once with 1 liter saturated NaCl to yield, after solvent removal, 139.2 g of crude 6,10,14-trimethylpentadeca-5,9-dien-2-one. Gas chromotographic analysis indicated 53.2% purity which represents an estimated theory yield from 10,11-dihydrofarnesene of 78.8%.

1. customat 25°
2. temperatureThe reaction mixture was cooled to 0°
3. additionabove was added dropwise over a 25-minute period
4. waitAfter this period
5. waitto ambient over a 40-minute period
6. distillationA portion of the ethanol (78.0 g) was distilled at this point
7. stirringby stirring the reaction mixture at 60°-65° for 2 hours under a slight vacuum
8. temperatureAfter cooling to 30°
9. additionof 10% aqueous NaOH was added over a 15-minute period
10. stirringthe reaction mixture was stirred at 70° for 4 hours
11. customthe layers were separated
12. extractionextracted with three 200-ml
13. washThe combined oils were washed once with 1 liter H2O and once with 1 liter saturated NaCl
14. customto yield
15. customafter solvent removal, 139.2 g of crude 6,10,14-trimethylpentadeca-5,9-dien-2-one
16. customyield from 10,11-dihydrofarnesene of 78.8%