1: NaBH4; aq. NaOH / ethanol / 6 h / -10 °C 2: 2162 g / TsOH / methanol / 15 h / 0 - 20 °C 3: 80 percent / Ph2PH; n-BuLi / tetrahydrofuran; hexane / 20 h / Heating 4: 100 percent / K2CO3; tetrabutylammonium bromide / acetone / 8 h / Heating 5: 83 percent / aq. KOH / methanol / 3 h / Heating View Scheme