1: ortho-dibromobenzene With isopropylmagnesium chloride lithium chloride complex in tetrahydrofuran T=-15°C; 2.5 h; 2: in tetrahydrofuran T=-20°C; 0.166667 h; 3: 2-chloro-pyridine-5-carbonyl chloride in tetrahydrofuran T=-10°C; 5.5 h;