1: 3-bromo-5-fluoro-pyridine With lithium diisopropyl amide in tetrahydrofuran; n-heptane T=-78°C; 0.75 h; 2: chloroformic acid ethyl ester in tetrahydrofuran; n-heptane 0.5 h; 3: With sodium hydrogencarbonate in tetrahydrofuran; n-heptane