Phosphorus oxide (P4O10) → 5,7-Difluoro-3,4-dihydronaphthalen-1(2H)-one

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Reaction Steps

120 g of Polyphosphoric acid and 12 g of phosphorous pentoxide are stirred to homogeneity at 60°. 43 g of 4-(2,4-Difluorophenyl)butyric acid are added and the mixture stirred for 11/2 hours at 80°, poured onto ice-water and extracted with ether. The combined organic phases are washed with sodium carbonate solution and sodium chloride solution, dried, stirred with a little active charcoal and evaporated. The crude product can be purified by silica gel chromatography (eluant:hexane/ethylacetate=4/1) or vacuum sublimation at 0.65 mbar/100°, m.p. 89°-91°.

Provenance & Evidence