1: camphorsulfonic acid / tetrahydrofuran / 1.5 h / Ambient temperature 2: DIBAL-H / tetrahydrofuran; hexane / 14 h / Ambient temperature 3: Zn, Me3Al / tetrahydrofuran / 2 h / -20 - 20 °C 4: 2N aq. HCl / methanol / 4 h / Ambient temperature 5: o-iodoxybenzoic acid / dimethylsulfoxide / 6 h / Ambient temperature View Scheme