Ammonia → Bis(4-fluorophenyl)methanimine

Participants

Reaction Conditions

Reaction Steps

4,4′-difluorobenzophenone (25 g) was dissolved in anhydrous toluene (800 mL), and the solution was cooled at −30° C. Titanium tetrachloride (21.4 mL) was dropwise added to the solution under nitrogen, and ammonia gas was passed through the mixture for about 20 minutes. Then the mixture was warmed up to room temperature and stirred over night. Saturated potassium carbonate aqueous solution (400 mL) was added to the reaction mixture, and the mixture was stirred for an additional 1 hour. The organic layer was separated and washed with water and saturated saline once respectively. The organic layer was dried over anhydrous sodium sulfate, and then the solvent was evaporated in vacuo to give crude product of 1,1-bis(4-fluorophenyl)methanimine (31.7 g). The crude product was dissolved in anhydrous toluene (80 mL), and trimethylsilylcyanide (171.86 mL) and zinc iodide (1.83 g) were added to the solution. Then the mixture was stirred at room temperature over night. The reaction mixture was washed with saturated sodium hydrogen carbonate aqueous solution and saturated saline in this order, and dried over anhydrous sodium sulfate. Then solvent was evaporated in vacuo to obtained crude product of 2-amino-2,2-bis(4-fluorophenyl)acetonitrile (30.84 g). The crude product was dissolved in anhydrous toluene (100 mL), and then 1M diisobutylaluminum hydride-toluene solution (500 mL) was dropwise added to the solution at −78° C. Then temperature of the mixture was raised by standing to room temperature, and the mixture was stirred over night. Sodium sulfate decahydrate was added to the reaction mixture, and the resultant mixture was stirred for one hour. Moreover, anhydrous magnesium sulfate was added to the reaction mixture, and the mixture was stirred for one hour. Then insolubles were removed by filtration. The filtrate was concentrated in vacuo, and then the obtained residue was purified by silica gel column chromatography (C-300; 100% ethyl acetate→100% methanol) to give the title compound (8.55 g).

Provenance & Evidence