Methyl 2-{[(benzyloxy)carbonyl]amino}-2-(dimethyl phosphono)acetate → Methyl(2Z)-2-{[(benzyloxy)carbonyl]amino}-3-(6-trifluoromethylpyridin-3-yl)acrylate

6-Trifluoromethylpyridine-3-carbaldehyde (4.85 g, 27.70 mmol) and methyl {[benzyloxycarbonyl]amino}(dimethoxyphosphoryl)acetate (9.17 g, 27.70 mmol, 1.0 equivalent) are dissolved in THF (70 ml) and cooled to −70° C. At −70° C., N,N,N,N-tetramethylguanidine (6.38 g, 55.39 mmol, 6.95 ml, 2.0 equivalents) is slowly added dropwise and then the mixture is stirred at −70° C. for 4 h, subsequently at RT for 12 h. The reaction mixture is concentrated, and extracted with ethyl acetate (2×100 ml) against water. The combined organic phases are washed with a saturated sodium chloride solution, dried over sodium sulfate and filtered. After concentration, the crude product is chromatographed (silica gel, eluent: toluene, then toluene: ethyl acetate 10:1). 6.93 g (66% of theory) of the title compound are obtained.