Hydrochloric Acid → 2-Fluoro-3-hydroxy-6-[4-(4-octyloxyphenyl)phenyl]pyridine

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Reaction Steps

7.95 ml (15.90 mmol) of a 2-molar lithium diisopropylamide solution in tetrahydrofuran/hexane/ethylbenzene are added dropwise at -78° C. to 5.00 g (13.25 mmol) of 2-fluoro-6-[4-(4-octyloxyphenyl)phenyl]pyridine (prepared as described in Example 6) in 1000 ml of tetrahydrofuran, and the mixture is stirred for 4 hours. 5.98 (31.80 mmol) of triisopropyl borate in 10 ml of tetrahydrofuran are then added dropwise at -78° C., and the reaction mixture is stirred overnight, during which it warms to room temperature. After addition of 20 ml of 10% hydrochloric acid and stirring at room temperature for 1 hour, sodium chloride solution is added, the mixture is extracted with ether, the ether phase is washed with sodium chloride, dried over sodium sulfate, filtered and concentrated. The residue is taken up in 200 ml of tetrahydrofuran, boiled with 40 ml of 17.5% hydrogen peroxide solution at 80° C. for 2 hours and then distributed between water and ether. The ether phase is washed with sodium sulfite solution and water, dried over sodium sulfate, filtered, evaporated to dryness, and the residue is chromatographed on silica gel using 8:2 toluene/THF, giving 1.7 g of 2-fluoro-3-hydroxy-6-[4-(4-octyloxyphenyl)phenyl]pyridine. ##STR25##

Provenance & Evidence