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

Multi-step reaction with 10 steps 1: TsOH*pyridine / CH2Cl2 / 15 h / 20 °C2: BuLi / tetrahydrofuran; hexane / 15 h / 0 - 20 °C3: NaOH / ethanol / 20 h / 20 °C4: 92 percent / EtMgBr / tetrahydrofuran; diethyl ether / 0 - 20 °C5: 75 percent / PCC / CH2Cl2 / 15 h / 0 - 20 °C6: BH3; Me2S; (R)-methyloxazaborolidine / toluene; tetrahydrofuran / 1 h / -30 °C7: 92 percent / imidazole; 4-(dimethylamino)pyridine / dimethylformamide; CH2Cl2 / 15 h / 20 °C8: CH2Cl2 / 2 h / 20 °C9: H2; K2CO3 / Pd/C / ethanol / 20 °C / 4654.33 Torr10: NaBH4; aq. NaOH / ethanol / 6 h / -10 °C