1: 96 percent / NaBH(OAc)3 / acetic acid / 1 h / 20 °C 2: 85 percent / DDQ / tetrahydrofuran / 21 h / 20 °C 3: 41 percent / HCl / ethyl acetate; dioxane / 20 °C 4: 82 percent / K2CO3 / dimethylformamide / 20 - 50 °C 5: 53 percent / t-BuOK / tetrahydrofuran / -5 - 45 °C View Scheme