1: 1-bromo-2,5-dimethyl-4-vinylbenzene With n-butyllithium in tetrahydrofuran; hexane; Petroleum ether T=-78°C; 0.666667 h; 2: With sulfur in tetrahydrofuran; hexane; Petroleum ether T=-85 - -75°C; 3: acetic anhydride in tetrahydrofuran; hexane; Petroleum ether T=-80°C; 0.05 h; Further stages.;