pyridinium p-toluenesulfonate in dichloromethane T=0 - 20°C; 2 h;

1: With n-butyllithium in tetrahydrofuran; hexanes T=-78°C; 0.166667 h; 2: With boric acid trimethyl ester in tetrahydrofuran; hexanes T=-78 - 20°C; 3: With hydrogenchloride in tetrahydrofuran; hexanes; water T=20°C; 1 h;