1: 1-bromo-3-chloro-5-fluorobenzene With magnesium in tetrahydrofuran Inert atmosphere; 2: boric acid trimethyl ester in tetrahydrofuran T=-70 - 20°C; 16 h; 3: With hydrogenchloride; water in tetrahydrofuran 1 h;

1.1: n-BuLi / tetrahydrofuran / -78 °C 1.2: tetrahydrofuran / -78 - 20 °C 2.1: HCl / tetrahydrofuran View Scheme