1.1: BuLi / tetrahydrofuran; hexane / 3 h / -78 °C 1.2: 70 percent / tetrahydrofuran; hexane / -78 - 0 °C 2.1: 6 percent / tetraphenylporphine; oxygen / CCl4 / 24 h / 20 °C / Irradiation View Scheme

1: 1.) butyllithium; 2.) H2O / 1.) hexane, THF, -70 deg C, 45 min, then -20 deg C, 1 h; 2.) -70 deg C 2: O2, tetraphenylporphyrine / CCl4 / 13 h / Ambient temperature; Irradiation View Scheme

chromium(VI) oxide in pyridine; dichloromethane T=20°C; 46 h;

chromium(VI) oxide in acetic acid T=10 - 20°C;

potassium dihydrogenphosphate; selenium(IV) oxide in 1,4-dioxane 60 h; Heating;