1: Dowex 50 x 2 (H+) / methanol / Ambient temperature 2: H2 / 10percent Pd/C / methanol / 36 h / 760 Torr View Scheme

Dowex 50(H+) in methanol

1: 85 percent / SnCl2 / methanol / 1 h / Ambient temperature 2: 85 percent / i-Pr2NEt / dimethylformamide / 0.5 h / 0 °C 3: 90 percent / Bu4NF / tetrahydrofuran / 0.5 h / Ambient temperature View Scheme