toluene-4-sulfonic acid in toluene T=60°C; P=150.015 Torr; 4 h;

1: With n-butyllithium in tetrahydrofuran; hexane T=-74 - -70°C; 1 h; 2: With tri-isopropoxy-borane in tetrahydrofuran; hexane T=-70 - 15°C; 2 h; 3: With hydrogenchloride; water in tetrahydrofuran; hexane T=60°C; pH=1; 1 h;