2,2-Difluoroethylamine

Typical Procedure:
To a stirred solution of 2,2-difluoroethylamine (193 mg, 2.38 mmol, 2.0 eq.) in CHCl₃ (20 mL), tert-butyl nitrite (294 mg, 2.86 mmol, 2.4 eq.) and acetic acid (28 mg, 0.48 mmol, 0.4 eq.) are added. The solution is heated at reflux whereas the mixture becomes deeply yellow. After 10 min, the heating is stopped, and the reaction mixture is cooled down to a room temperature by external water bath. Methyl propiolate (100 mg, 1.19 mmol, 1.0 eq.) is added at once. The reaction mixture is left at room temperature for 24 h. The solvent is evaporated under vacuum. The formed oily residue is purified by column chromatography on silica gel using hexane-EtOAc (2:1) as an eluent, to afford the pure product (159 mg, 0.90 mmol, 76% yield) as a colorless solid.