75 mg (0.23 mmol) of N-tert-butoxycarbonyl-2,2-difluoro-2-(3-butoxyphenyl)-ethylamine are dissolved in dry DMF (5 mL). The solution is cooled to 0° C. and NaH (6.7 mg; 1.2 eq) is added. The solution is stirred at RT for 10 min, then cooled again to 0° C. and 2-chloro-N,N-dimethylpropanamide (31 mg; 0.23 mmol) are added. After 4 hours a further 1.2 eq of NaH (6.7 mg) are added. The reaction mixture is stirred overnight at RT, then quenched with water, evaporated, the residue taken up with water and EtAc. The organic layer is separated and the water layer extracted three times with EtAc. The combined organic phases are dried over anhydrous Na2SO4, filtered and evaporated. The resulting crude residue is flash-chromatographed (eluant: petroleum ether/EtAc, 9/1 to 8/2). 2-[N-tert-butoxycarbonyl-2,2-difluoro-2-(3-butoxyphenyl)-ethylamino]-N,N-dimethylpropanamide (84 mg; 81%) is obtained as pale yellow oil.
