1: 53 percent / SeO2 / 2-methyl-propan-2-ol; benzene / Heating 2: 61 percent / CrO3, H2SO4 / acetone / 1 h / -10 °C 3: 73.8 percent / acetic acid (glacial) / tetrahydrofuran; H2O / 168 h / Ambient temperature View Scheme

1: 53 percent / SeO2 / 2-methyl-propan-2-ol; benzene / Heating 2: 96 percent / acetic acid (glacial) / tetrahydrofuran; H2O / 80 h / Ambient temperature View Scheme

1: 94 percent / pyridine / 10 h / 4 °C 2: 67 percent / SeO2 / 2-methyl-propan-2-ol; benzene / Heating 3: 88 percent / acetic acid (glacial) / tetrahydrofuran; H2O / 162 h / Ambient temperature View Scheme