Under argon, 1.73 g (17.95 mmol) of sodium tert-butoxide were weighed out into a dry flask, and 40 ml of abs. toluene were added. 5.2 g (14.96 mmol) of tert-butyl 3-(3-bromo-4-chlorophenyl)-2,2-dimethylpropanoate, 1.96 ml (17.95 mmol) of benzylamine, 685 mg (0.75 mmol) of tris(dibenzylideneacetone)dipalladium and 373 mg (0.60 mmol) of (+/−)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl were added in succession. The reaction mixture was stirred at 110° C. for 2.0 h, then cooled to RT and stirred at this temperature overnight. Saturated aqueous ammonium chloride solution and ethyl acetate were then added, and the reaction mixture was filtered off with suction through kieselguhr. After phase separation, the organic phase was washed with saturated ammonium chloride solution and saturated sodium chloride solution, dried over magnesium sulphate and concentrated under reduced pressure. The crude product was purified by preparative HPLC (mobile phase acetonitrile/water). This gave 2.78 g of the title compound (50% of theory).
