silica gel in toluene Heating;

1: 52 percent / silica gel / toluene / Heating 2: P2S5, NaHCO3 / bis-(2-methoxy-ethyl) ether / 3 h / 70 - 80 °C 3: 6 g / hydrazine / tetrahydrofuran / 0.5 h / 45 - 80 °C 4: 80 percent / 1 h / 80 °C View Scheme

1: 52 percent / silica gel / toluene / Heating 2: P2S5, NaHCO3 / bis-(2-methoxy-ethyl) ether / 3 h / 70 - 80 °C 3: 6 g / hydrazine / tetrahydrofuran / 0.5 h / 45 - 80 °C 4: 80 percent / 1 h / 80 °C 5: 98 percent / KOH / methanol View Scheme