Na2SO4 (1.09 g, 7.7 mmol) was added to a solution of the ethyl (RS)-(3-amino-5-ethyl-phenyl)-(4-cyano-phenylamino)-acetate (250 mg, 0.77 mmol) obtained in Example 223.4 and 1-methyl-4-piperidone (174 mg, 1.54 mmol) in acetic acid (5 ml) and the mixture was stirred for 15 min. at room temperature. The mixture was subsequently cooled to 0° C. and NaHB(OAc)3 (489 mg, 2.31 mmol) was slowly added portionwise. After 30 min. a saturated solution of NaHCO3 was added and the mixture was extracted with EtOAc. The organic phase was dried and filtered, and the filtrate was concentrated. The residue was purified by chromatography (SiO2, CH2Cl2/MeOH 9:1). There were obtained 287 mg (89%) of ethyl (RS)-(4-cyano-phenylamino)-[3-ethyl-5-(1-methyl-piperidin-4-ylamino)-phenyl]-acetate as a yellowish solid; MS: 421 ([M+H]+).
