18-crown-6 ether; phosphonoacetic acid P,P-bis(2,2,2-trifluoroethyl)methyl ester; potassium hexamethylsilazane in tetrahydrofuran; toluene T=-78°C; Horner-Wadsworth-Emmons olefination; 4 h; Inert atmosphere;

1: With 1,8-diazabicyclo[5.4.0]undec-7-ene; sodium iodide in tetrahydrofuran T=-78°C; Horner-Wadsworth-Emmons reaction; 2: With potassium hydroxide in methanol T=20°C; 0.25 h;