Cesium carbonate → 5-Bromo-4-chloro-2-[isopropoxycarbonyl-(3-methoxycarbonyl-propyl)-amino]-benzoic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

To a mixture of 5-Bromo-4-chloro-2-isopropoxycarbonylamino-benzoic acid methyl ester (2.52 g, 7.19 mmol) and cesium carbonate (4.68 g, 14.4 mmol) in DMF (35 ml) under nitrogen was added methyl 4-bromobutyrate (2.60 g, 14.4 mmol) dropwise. The reaction mixture was heated to 60° C. for 4 hours and then cooled to room temperature. The mixture was diluted with ethyl acetate (100 ml), and then washed with 0.1N HCl(aq) (100 ml) and brine (3×100 ml). The organic layer was dried over Na2SO4 and concentrated under reduced pressure. Purification by silica gel chromatography (gradient eluent, 0-20% ethyl acetate in hexane) provided 5-Bromo-4-chloro-2-[isopropoxycarbonyl-(3-methoxycarbonyl-propyl)-amino]-benzoic acid methyl ester (2.78 g, 86%) as oil. MS (ES+): 450, 452 (M+H).

Provenance & Evidence