Hydrochloric Acid → Oxycinchophen

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A 1 L round-bottomed flask was charged with 360 mL of water and LiOH.H2O (34.3 g, 800 mmol) and stirred at 50-60° C. Isatin (30 g, 200 mmol) was added and the reaction stirred for 30 minutes at 50-60° C. The (α-acetoxy acetophenone (40.95 g, 230 mmol, 1.15 equiv.) was added as a solid in one portion and the solution heated at 80-85° C. until <5% by PAR isatin remains as shown by HPLC (typically 3 hours). The reaction was cooled to room temperature, diluted with water (90 mL) and tert-butyl methyl ether (“TBME”) (210 mL) and transferred to a separatory funnel. The mixture was shaken well and the aqueous layer drained into an Ehrlenmeyer flask. The aqueous layer was acidified to pH=3.0-3.5 using conc. HCl (˜61 mL) and monitored with a pH meter. The suspension of yellow solid was heated to 60-70° C., and held at that temperature for 5-10 minutes and filtered through a Buchner funnel. The flask was rinsed with 90 mL of water at 60-70° C. and the filter cake was washed with this rinse. The solid was suction dried for 10 minutes and charged back to the 1 L flask. The flask was charged with 600 mL of water, the suspension heated to 60-70° C., held there for 10 minutes, and filtered through a Buchner funnel. The flask was rinsed with 150 mL of water at 60-70° C. and the filter cake washed with this rinse. The filter cake was dried in a vacuum oven at 80-90° C. and <1 mm Hg. After drying to constant weight, the product 3-hydroxy-2-phenylquinoline-4-carboxylic acid (82%) was obtained as a bright yellow solid: mp 206° C.; IR (cm−1) 3430, 2600, 1634; 1H NMR (300 MHz, DMSO-d6) δ8.75 (1H, δ, J=8.2 Hz), 8.01 (3H, m), 7.59 (5H, m); 13C NMR (75 MHz,DMSO-d6) δ171.03, 153.98, 151.38, 139.68, 135.62, 129.60, 129.38, 128.27, 127.83, 126.27, 125.22, 124.54, 115.26.

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