1: With n-butyllithium in tetrahydrofuran; hexanes T=-90°C; 0.5 h; 2: With boric acid trimethyl ester in tetrahydrofuran; hexanes T=-90°C; 0.5 h; 3: With hydrogenchloride; water in tetrahydrofuran; hexanes T=-90 - 30°C; 0.5 h;