1: 1,2-dichloro-1-(methylthio)ethene With n-butyllithium in tetrahydrofuran; hexane T=-78 - -10°C; 1.5 h; 2: With selenium in tetrahydrofuran; hexane cooling; 3: carbon diselenide; 3-thiocyanatopropionic acid methyl ester in tetrahydrofuran; hexane T=-100 - -90°C;