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 0.5 N 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 0.5 N 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