1: p-toluenesolfonic acid; water / tetrahydrofuran 2: 91 percent / Pd(OAc)2; bis(diphenylphosphanyl)propane; Ag2CO3 / toluene / 24 h / 107 °C 3: 57 percent / SeO2; NaH2PO4 / dioxane / 3 h / 150 °C 4: methanol 5: diisobutylaluminum hydride 6: sodium cyanoborohydride / H2O View Scheme