Trifluoroacetic acid → 2-[4-(4-Bromophenyl)piperazine-1-sulfonylmethyl]-3-methylbutyric acid

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Reaction Steps

Trifluoroacetic acid (10 ml) was added slowly to a solution of 2-[4-(4-bromophenyl)piperazine-1-sulfonylmethyl]-3-methylbutyric acid tert-butyl ester (2.26 g) in dichloromethane (50 ml). After stirring at room temperature for 3.5 h., the solvents were removed under vacuum, and the residue azeotroped twice with 1:1 dichloromethane/hexane (30 ml). The residue was then dissolved in 1 M sodium hydroxide (20 ml) and washed with diethyl ether (50 ml). The aqueous phase was then acidified to pH 3-4 with citric acid and extracted with dichloromethane (60 ml, then 2×20 ml). The combined dichloromethane extracts were then washed with water (20 ml), saturated brine (20 ml), dried (MgSO4) and the solvents removed under reduced pressure to provide the title compound as a white solid (3.81 g, 79%).

Provenance & Evidence