1.1: n-butyllithium / tetrahydrofuran; hexane / 2 h / -78 °C / Inert atmosphere 1.2: Inert atmosphere 2.1: pyridinium chlorochromate / dichloromethane / 4 h / 20 °C / Inert atmosphere 3.1: potassium hydrogen persulfate; 18-crown-6 ether; sodium hydrogencarbonate; acetone / water; acetonitrile / 0 °C / Inert atmosphere 4.1: benzene / UV-irradiation; Inert atmosphere View Scheme