反应详情

300 g. of a 10% solution of lithium diisopropylamide in hexane was introduced into 90 ml. of absolute tetrahydrofuran, cooled to 0°, and combined dropwise under agitation with a solution of 28 g. of isobutyric acid methyl ester in 150 ml. of absolute tetrahydrofuran. The reaction solution was stirred for one hour at 0°, then cooled to -40° and subsequently added to a solution of 58 g. of 4-bromo-2-methyl-2-butene (dimethylallyl bromide) in 60 ml. of absolute dimethyl sulfoxide maintained at -20°. While allowing the temperature of the solution to rise to room temperature, the solution was stirred for 6 hours and then combined with saturated sodium chloride solution. The organic phase was separated, the aqueous phase was extracted five times with respectively 200 ml. of a 1/1 mixture of ether and hexane. The combined organic phases were washed neutral with 0.5N hydrochloric acid and saturated sodium chloride solution, dried over magnesium sulfate, and concentrated on a forced circulation evaporator. The residue was distilled under vacuum, thus obtaining 20.7 g. of the title compound, b.p. (13 mm.) 74°.

1. temperaturecooled to -40°
2. additionsubsequently added to a solution of 58 g
3. customto rise to room temperature
4. stirringthe solution was stirred for 6 hours
5. customThe organic phase was separated
6. extractionthe aqueous phase was extracted five times with respectively 200 ml
7. additionof a 1/1 mixture of ether and hexane
8. washThe combined organic phases were washed neutral with 0.5N hydrochloric acid and saturated sodium chloride solution
9. dry with materialdried over magnesium sulfate
10. concentrationconcentrated on a forced circulation evaporator
11. distillationThe residue was distilled under vacuum
12. customthus obtaining 20.7 g