反应详情

A solution of di-isopropylamine (4.04 g) and butyl-lithium (25 ml, 1.60 M in hexane) in dry tetrahydrofuran (40.0 ml), stirred at -78° under dry nitrogen, was treated over 5 minutes with t-butyl acetate (4.64 g). To this solution was added, over 5 minutes, a solution of α,α'-dibromo-m-xylene (11.60 g) and dry hexamethylphosphoramide (1.42 g) in dry tetrahydrofuran (8.0 ml). The resulting yellow solution was stirred at -78° for 1/2 hour, then allowed to warm to room temperature over 3 hours. Excess ice-water was added, and the mixture extracted with ether, and the extract washed with 1 N hydrochloric acid (60 ml) then water. The dried extract was concentrated in vacuo, to give a yellow oil which was purified by column chromatography on silica, eluting with 1:1 ether:hexane, giving t-butyl 3-(3-bromomethylphenyl)propionate as a colourless oil. Using the method described in the last foregoing paragraph this was converted to the desired diethylester which was used in each of Examples 22 to 25.

1. additionTo this solution was added, over 5 minutes
2. extractionthe mixture extracted with ether
3. washthe extract washed with 1 N hydrochloric acid (60 ml)
4. extractionThe dried extract
5. concentrationwas concentrated in vacuo
6. customto give a yellow oil which
7. customwas purified by column chromatography on silica
8. washeluting with 1:1 ether