1: trimethyl trithioorthoformate With n-butyllithium in tetrahydrofuran; hexane T=-78°C; Metallation; 2: acetaldehyde in tetrahydrofuran; hexane T=-78 - 20°C; Addition;

in tetrahydrofuran

in tetrahydrofuran 40 h; from -40 deg C to room temperature;

boron trifluoride diethyl etherate; mercury(II) oxide in tetrahydrofuran