1: With n-butyllithium in tetrahydrofuran; hexane T=-60°C; 0.5 h; 2: With boric acid trimethyl ester in tetrahydrofuran; hexane T=-60 - 20°C; 4 h; 3: With hydrogenchloride in water T=5°C; pH=1;

1: 5-Bromobenzo(b)-furan With n-butyllithium in tetrahydrofuran; hexane T=-60 - -30°C; 1.25 h; 2: tri-isopropoxy-borane in tetrahydrofuran; hexane T=-60 - 20°C; 3: water With hydrogenchloride in tetrahydrofuran; hexane T=20°C; 1 h;