Diisopropylamine → t-Butyl 3-(3-bromomethylphenyl)propionate

Participants

Reaction Steps

A solution of di-isopropylamine (4.04 g) and butyl-lithium (25 ml, 160 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 hexamethyl phosphoramide (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 1N 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.

Provenance & Evidence