To a stirred solution of (RS)-2-(4-bromo-3-fluoro-phenyl)-morpholine-4-carboxylic acid tert-butyl ester (1.57 g) and benzophenone imine (1.15 ml) in toluene (40 ml) was added sodium tert-butoxide (691 mg). The reaction mixture was purged with argon for 10 min. (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (280 mg) and tris(dibenzylideneacetone)dipalladium(0) (120 mg) were added and the reaction mixture was heated to 100° C. and stirred for 1 h. The reaction mixture was poured into water and extracted twice with EtOAc. The organic layers were dried over Na2SO4 and concentrated in vacuo. The residue was purified by flash column chromatography (silica gel; gradient: 0% to 30% EtOAc in hexanes) to afford (RS)-2-[4-(benzhydrylidene-amino)-3-fluoro-phenyl]-morpholine-4-carboxylic acid tert-butyl ester (2.215 g, quant.) as a yellow viscous oil. MS (ISP): 461.3 ([M+H]+), 405.4 ([M+H—C4H8]+), 361.3 ([M+H—C4H8—CO2]+).
