1: 1-bromo-3-chlorobenzene With magnesium chloride in 2-methyl tetrahydrofuran 2: With lithium diisopropyl amide in tetrahydrofuran; 2-methyl tetrahydrofuran; n-heptane T=-78 - -75°C; 1 h; 3: N,N-dimethyl-formamide With citric acid more than 3 stages;

durch Oxydation;