1: 60 percent / DBU / 0.75 h / Ambient temperature 2: 77 percent / t-BuOK, KMnO4 / 2-methyl-propan-2-ol 3: 64 percent / t-BuOK / tetrahydrofuran / 0.5 h / 20 °C View Scheme

1: acetic acid, 15-crown-5 / CH2Cl2; H2O / 10 h / Ambient temperature 2: HOAc, H2SO4, H2O / 10 h / 100 °C 3: 1. SOCl2 / 1. reflux, 30 min 2. toluene, r.t., 30 min 4: potassium tert-butoxide / tetrahydrofuran / 0.5 h / 25 °C View Scheme

1: acetic acid, 15-crown-5 / CH2Cl2; H2O / 10 h / Ambient temperature 2: 80 percent / H2SO4 / 12 h / 80 °C 3: 68 percent / MeONa / tetrahydrofuran / 0.5 h / 15 °C View Scheme