1: 1-bromo-3-methyl-1-butyne in diethyl ether T=18 - 20°C; Metallation; 2: C13H15NS in diethyl ether T=20°C; Grignard reaction; 15 h; 3: With hydrogenchloride in diethyl ether; water T=20°C; Hydrolysis; 2 h;