Citric Acid → HCID 69414718, compound

Participants

Reaction Conditions

Reaction Steps

Sodium hydride (280mg of a 60% dispersion in mineral oil, 7 mmol) was added to a solution of 7-trifluoromethoxy-1H-indole-2-carboxylic acid ethyl ester (1.53 g, 5.6 mmol) and (S)-5-methyl-2,2-dioxo-[1,2,3]oxathiazolidine-3-carboxylic acid tert-butyl ester (1.53 g, 6.45 mmol) in N,N-dimethylformamide (15 mL) at 0° C. The solution was allowed to reach room temperature and stirred 36 h. Further amounts of sodium hydride (56 mg) and (S)-5-methyl-2,2-dioxo-[1,2,3]oxathiazolidine-3-carboxylic acid tert-butyl ester (306 mg) were added to complete the reaction. To the solution was added 10% aq. citric acid solution and the mixture stirred 1 h at room temperature. The organics were extracted with ethyl acetate (2×), the combined organic phases washed with sat. aq. NaHCO3 solution and brine, dried (Na2SO4), and evaporated. The residue was dissolved in dichloromethane (25 mL), cooled to 0° C. and treated with trifluoroacetic acid (12 mL). After removal of the ice bath, the solution was stirred for 30 min and evaporated under reduced pressure. The residue was taken up in methanol (20 mL) and K2CO3 (2.52 g, 19.5 mmol) added, and the mixture stirred 15 h at room temperature. The mixture was filtered, the filtrate diluted with ethyl acetate, washed with water, dried (Na2SO4) and evaporated. The residue was purified by column chromatography on silica gel (hexane/ethyl acetate gradient) to afford the product as a pale yellow foam (89 mg, 64%). ISP-MS: m/e=285.1 (M++H).

Provenance & Evidence