Phosphorus oxide (P4O10) → 5,7-Difluoro-3,4-dihydronaphthalen-1(2H)-one
Reaction equation
O=P12OP3(OP(OP(O3)(O1)=O)(=O)O2)=O.[F:15][C:16]1[CH:21]=[C:20]([F:22])[CH:19]=[CH:18][C:17]=1[CH2:23][CH2:24][CH2:25][C:26]([OH:28])=O>>[F:15][C:16]1[CH:21]=[C:20]([F:22])[CH:19]=[C:18]2[C:17]=1[CH2:23][CH2:24][CH2:25][C:26]2=[O:28]Participants
3
Procedure
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°.
Workup
- additionpoured onto ice-water
- extractionextracted with ether
- washThe combined organic phases are washed with sodium carbonate solution and sodium chloride solution