1: diethyl (1-oxopropyl)phosphonate With potassium hexamethylsilazane in tetrahydrofuran; toluene T=-78°C; 3 h; 2: trans-crotonyl chloride in tetrahydrofuran; toluene T=25°C; 15 h;

1: With potassium hexamethylsilazane in tetrahydrofuran; toluene T=-78°C; 3 h; 2: T=25°C; 15 h;