Trifluoroacetic acid → 3-Methyl-2-[4-(4-pyridin-3-yl-phenyl)piperazine-1-sulfonylmethyl]butyric acid

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Reaction Steps

2-Chlorosulfonylmethyl-3-methylbutyric acid tert-butyl ester (0.072 g) [preparation described in WO-A-98/05635] was added as a solution in dichloromethane (2 ml) to a stirred mixture of 1-(4-pyridin-3-yl-phenyl)piperazine (0.053 g) and triethylamine (40 μl) and the resultant solution stirred at room temperature for 2 h. Trifluoroacetic acid (4 ml) was then added dropwise, and the mixture stirred for a further 2 h. The solvent were removed under reduced pressure and the residue azeotroped with 1:1 dichloromethane/hexane (2×10 ml). The residue was then diluted with diethyl ether (20 ml) and extracted with 1 M sodium hydroxide (10 ml) followed by 0.5 M sodium hydroxide (10 ml). The combined aqueous extracts were then washed with diethyl ether (20 ml), then cautiously acidified to pH 5 with acetic acid, forming a precipitate. The mixture was then extracted with ethyl acetate (3×20 ml). The combined organic extracts were washed with water (2×10 ml), saturated brine (10 ml), dried (Na2SO4) and reduced in vacuo to give the title compound as a pale green solid (0.085 g, 93%).

Provenance & Evidence