1: 92 percent / potassium t-butoxide / tetrahydrofuran; dimethylformamide / 1.) -20 deg C, 1 h, 2.) 20 deg C, 1 h 2: 80.4 percent / ethyl alcohol, sodium / tetrahydrofuran / 12 h 3: 48 percent hydrobromic acid / propan-2-ol / 3 h / 50 °C View Scheme

1.1: 85 percent / dimethylformamide / 24 h / 20 °C 2.1: BuLi / hexane; tetrahydrofuran; hexamethylphosphoric acid triamide / 0.5 h / -70 °C 2.2: 75.8 percent / hexane; tetrahydrofuran; hexamethylphosphoric acid triamide / 3 h / -70 - 20 °C 3.1: EtNH2; Li / tetrahydrofuran / 0.5 h / -78 °C 3.2: 86.1 percent / isoprene; NH4Cl / tetrahydrofuran 4.1: 93 percent / aq. HCl / methanol; hexane / 4 h / 40 °C View Scheme

1: (i) Mg, Et2O, (ii) /BRN= 2066988/ 2: AgO, HNO3 / H2O; dioxane View Scheme

1: NaH / dimethylsulfoxide; tetrahydrofuran / Ambient temperature 2: 30percent KOH/MeOH / 0 °C 3: BF3*OEt2 / CCl4 / 0.17 h / -15 °C 4: activated MnO2 / CCl4 View Scheme

pyridine; phosphorus tribromide in diethyl ether

phosphorus tribromide in diethyl ether