1: pyridine / dichloromethane / 2 h / 0 - 20 °C 2: hydrazine hydrate / methanol / 4 h / 90 °C / |Sealed tube 3: dihydrogen peroxide; sodium hydroxide / tetrahydrofuran; water / 72 h / 20 °C 4: copper diacetate; 1,10-phenanthroline; triethylamine; oxygen / toluene; acetonitrile / 5 h / 20 °C View Scheme