1: tert-butyl 4-(diethoxyphosphoryl)-3-oxobutanoate With sodium hydride in tetrahydrofuran; mineral oil T=25°C; 0.0833333 h; Inert atmosphere; 2: With n-butyllithium in tetrahydrofuran; hexane; mineral oil T=-30°C; 0.0833333 h; Inert atmosphere; 3: acetaldehyde in tetrahydrofuran; hexane; mineral oil T=-30 - 20°C; Horner-Wadsworth-Emmons reaction; Inert atmosphere; diastereoselective reaction;