Hydrochloric Acid → 2-Propyl-7-fluoro-1,2,3,4-tetrahydro-6-naphthol

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Reaction Steps

200 g of the 2-propyl-1,2,3,4-tetrahydro-6-naphthol obtained in (7-1) was dissolved in 1000 ml of dichloromethane, 5 g of sodium trifluoromethanesulfonate was added, and the mixture was stirred vigorously. 243 g of N,N′-difluoro-2,2′-bipyridinium bistetrafluoroborate was gradually added to the reaction mixture, and the resulting mixture was stirred for a further 5 hours at room temperature. Water, and then a 10% aqueous solution of sodium hydroxide were added, any excess fluorinating reagent was decomposed, and following restoration to an acidic state by addition of dilute hydrochloric acid, the organic layer was separated. The aqueous layer was extracted with dichloromethane, the extract was combined with the separated organic layer, and this combined organic extract was washed with water and a saturated aqueous solution of sodium chloride, before being dried over anhydrous sodium sulfate. The crude product obtained by removal of the solvent by evaporation was separated and purified by silica gel column chromatography (toluene), to obtain 57.0 g of 2-propyl-5-fluoro-1,2,3,4-tetrahydro-6-naphthol, and 85.5 g of 2-propyl-7-fluoro-1,2,3,4-tetrahydro-6-naphthol.

Provenance & Evidence