General procedure for the synthesis of 4,4-difluorocyclohexanecarbonitrile and 4-fluorocyclohex-3-ene-1-carbonitrile from 4-oxocyclohexanecarbonitrile: A solution of (diethylamino)sulfur trifluoride (46.7 g, 289 mmol) in dichloromethane (200 mL) was added slowly and dropwise at 0 °C to a solution of 4-oxocyclohexanecarbonitrile (32.4 g, 263 mmol) in dichloromethane ( 400 mL) solution. The reaction mixture was stirred at this temperature for 2 hours and then the reaction was quenched with deionized water (100 mL). The organic phase was separated and dried over anhydrous magnesium sulfate. After concentrating the solvent, a 7:3 mixture of 4,4-difluorocyclohexanecarbonitrile and 4-fluorocyclohex-3-ene-1-carbonitrile was obtained. Another 77% m-chloroperoxybenzoic acid (MCPBA, 45 g, 200 mmol) was stirred in chloroform (600 mL) for 30 min and the solution was dried over anhydrous sodium sulfate and filtered. A mixture of 4,4-difluorocyclohexanecarbonitrile and 4-fluorocyclohex-3-ene-1-carbonitrile obtained above was added to the MCPBA solution and stirred at room temperature for 18 hours. After completion of the reaction, the reaction mixture was washed with 1.5 M sodium hydroxide solution (3 x 300 mL) and the organic phase was dried with anhydrous magnesium sulfate. After concentrating the solvent, the residue was distilled under reduced pressure to give the pure target compound 4,4-difluorocyclohexanecarbonitrile as a colorless liquid. Yield 18.2 g (47%).1H NMR (400 MHz, chloroform-d) δ 1.86-1.96 (m, 1H), 1.95-2.03 (m, 5H), 2.03-2.22 (m, 2H), 2.68-2.85 (m, 1H).
