1: 1.) K-tert-C4H9; 2.) O2, Bengalrosa B / <18>crown-6 / 1.) CH2Cl2, 4h, room temp.; 2.) CH2Cl2, 30 min, irradiation 2: 86 percent / pyridiniumchlorochromate, NaAc*3H2O / CH2Cl2 / 0.42 h / Ambient temperature 3: 2.) CH3COOH, CF3COOH, H2O / 1.) CH2Cl2, room temp., 30 min, irradiation; 2.) THF, 15 degC, 24h 4: 95 percent / 1.5percent methanolic HCl / 16 h / Ambient temperature View Scheme