To a solution of 2,5-difluorobenzaldehyde (0.765 mL, 7.04 mmol) in ethanol (15 mL) was added methyl 4-nitrobutyrate (0.901 mL, 7.04 mmol) and the mixture stirred for 5 minutes. To the reaction mixture was added 2-(2-fluorophenyl)ethylamine (0.87 mL, 7.04 mmol) and the mixture stirred for 10 minutes. To the mixture was added sodium acetate (0.577 g, 7.04 mmol) followed by glacial acetic acid (0.806 mL, 14.07 mmol) and the mixture heated at reflux temperature for 48 h. The solvent was removed in vacuo and to the yellow oil was added saturated aqueous sodium hydrogen carbonate (25 mL) and the aqueous phase extracted with ethyl acetate (4×25 mL). The combined organic phases were washed with saturated aqueous brine (1×25 mL), dried with anhydrous sodium sulfate, filtered and the solvent removed in vacuo. The yellow oil was purified by column chromatography (silica gel Biotage 40S) eluting with ethyl acetate/hexane (gradient from 0% to 60%) to give the racemic trans title compound as a yellow gum. LC/MS 379.2 (M+1).
