1: (ethyl)-triphenylphosphonium bromide With sodium hexamethyldisilazane in tetrahydrofuran T=-78 - 0°C; 1.25 h; Inert atmosphere; 2: (R)-2-Methyl-3-trityloxy-propionaldehyde in tetrahydrofuran T=-78 - 0°C; 2.16667 h; Inert atmosphere; 3: methanol Further stages;