Chlorotrifluoroethylene → 7-Fluoro-1,2,3,4-tetrahydronaphthalen-1-one

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Reaction Conditions

Reaction Steps

In a specially designed Kel-F reactor (cylindrical shape 1.25"od×3"h equipped with a screw cap and N2 inlet-outlet) was placed hydrogen fluoride-pyridine 6:4 solution (10 mL, prepared by diluting commercially available hydrogen fluoride-pyridine 7:3 solution with dry pyridine). 7-amino-tetralone (644 mg, 4.0 mmol), (Example 35, Step A) was added under N2 and the solution was cooled to 0°. Sodium nitrite (304 mg, 4.4 mol, 1.1 eq) was added in portions and the mixture was stirred for 30 minutes. The mixture was then heated at 90° C. for 1 hour with stirring. The reaction mixture was quenched with approx. 60 mL of ice/water and the solid that separated extracted with methylene chloride (3×30 mL). The combined extracts were washed with water and brine, dried over magnesium sulfate, filtered and evaporated to dryness under vacuum at room temperature. Purification by flash chromatography on silica, eluting with ethyl acetate/hexane (5:95), afforded pure 7-fluoro- 1-tetralone (367 mg, 2.2 mmol, 56%). 1H NMR (300 MHz, CDCl3): 2.13 (m,2H), 2.65 (t,7 Hz,2H), 2.94 (t,7 Hz,2H), 7.1-7.3 (m,2H), 7.69 (dd;2,8 Hz;1H). EI-MS: calculated for C10H9FO 164; found 164 (M+,71%).

Provenance & Evidence