Hydrochloric Acid → (1R,2S)-2-(((2,4-Dimethylpyrimidin-5-yl)oxy)methyl)-2-(3-fluorophenyl)cyclopropanecarboxylic acid

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Reaction Conditions

Reaction Steps

((1R,2S)-2-(((2,4-dimethylpyrimidin-5-yl)oxy)methyl)-2-(3-fluorophenyl)cyclopropyl)methanol (11, 87.5 g, 290 mmol, 1.0 equiv.) was dissolved in toluene (390 mL) To the mixture was added pH 7 buffer (107 g, prepared from 4.46 g of sodium phosphate dibasic and 7.79 g of sodium phosphate monobasic in 94.4 mL of water) and 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) (0.93 g, 5.9 mmol, 0.02 equiv.). The mixture was cooled to 0° C. and sodium hypochlorite solution (5% active chlorine, 383 mL, 304 mmol, 1.05 equiv.) was added dropwise, maintaining the internal temperature below 9° C. The mixture was allowed to warm to room temperature and stirred for 2 h. To the mixture was added aqueous hydrochloric acid (2.0 M, 8.73 mL, 0.05 equiv.) followed by a solution of sodium chlorite (36.0 g, 318 mmol, 1.1 equiv.) in water (87 mL), maintaining the internal temperature below 26° C. The mixture was stirred at room temperature for 4 h, and then cooled to 10° C. A solution of sodium thiosulfate (92 g, 579 mmol, 2.0 equiv.) in water (177 mL) was added, maintaining the internal temperature below 20° C. The mixture was stirred for 20 min, and then aqueous sodium hydroxide solution (4 N, 87 mL, 348 mmol, 1.2 equiv.) was added to achieve ca. pH=13. The mixture was heated to 80° C. for 4 hours, then cooled to room temperature. Stirring was halted and the phases allowed to split. The lower aqueous phase was collected and the upper organic phase was washed once with 4 N sodium hydroxide solution (17 mL). The combined aqueous phases were acidified with aqueous hydrochloric acid solution (4 N, 17 mL) to pH=4 and extracted with ethyl acetate (2×470 mL). The combined organic phases were washed with ca. 20% aqueous NaCl solution (175 mL) The organic phases were concentrated by rotary evaporation to yield 96.84 g of crude oil. A portion (74 g) of this crude oil was dissolved in acetonitrile (400 mL) and concentrated to dryness by rotary evaporation. Another portion of acetonitrile (400 mL) was added and the mixture was again concentrated to dryness. To the residue was added acetonitrile (370 mL). The mixture was heated to 65° C. resulting in a clear solution. The mixture was cooled to room temperature, then to 0° C. and held at this temperature for 6 h. The mixture was filtered and the wet cake was washed with acetonitrile (2×74 mL). The cake was dried under vacuum with a nitrogen sweep, then in a vacuum oven at 20 torr and 40° C. to afford (1R,2S)-2-(((2,4-dimethylpyrimidin-5-yl)oxy)methyl)-2-(3-fluorophenyl)cyclopropanecarboxylic acid (13, 56.9 g, 80% yield) as an off-white crystalline solid.

Provenance & Evidence