toluene-4-sulfonic acid in water; acetone T=0 - 5°C; 0.5 h;

cobalt(II) 2,4-pentanedionate; lithium bromide in tetrahydrofuran; 1-methyl-pyrrolidin-2-one T=-30 - 0°C; 0.5 h;

1: n-butyl-triphenylphosphonium bromide With sodium hexamethyldisilazane in tetrahydrofuran T=-40 - 20°C; 2: fumaraldehyde mono(dimethyl) acetal in tetrahydrofuran T=-75 - 20°C; Wittig olefination;

1: phosphonoacetic acid P,P-bis(2,2,2-trifluoroethyl)methyl ester With sodium hexamethyldisilazane; 18-crown-6 ether in tetrahydrofuran; toluene T=-70°C; 0.25 h; 2: trans,cis-2,4-octadienal in tetrahydrofuran; toluene T=-75°C; Horner-Wadsworth-Emmons olefination; 1 h;

potassium carbonate in water T=20°C; Horner-Wadsworth-Emmons olefination; Title compound not separated from byproducts;