1: 72 percent / tetrahydrofuran / 1 h / 0 °C 2: 80 percent / MnO2, pyridine / CH2Cl2 / 0.5 h / Heating 3: 72 percent / BF3*OEt / tetrahydrofuran / 0.5 h / 50 °C 4: 61 percent / toluene / 20 h / Heating 5: 95 percent / TFA / toluene / 0.5 h / Heating 6: 68 percent / DDQ / benzene / 5 h / Heating 7: 87 percent / aq. NaOH / methanol; tetrahydrofuran / 3 h / Heating View Scheme

1: 1) n-Bu4NHSO4, NaOH / 1) CH2Cl2, 0 deg C, 2) CH2Cl2, 0 - 5 deg C, 25 min 2: 100 percent / NaBH4 / tetrahydrofuran; aq. ethanol / 1.25 h / 0 - 5 °C 3: 1) lithium diisopropylamide / 1) THF, hexane, a) -75 deg C, 90 min, b) rt, 30 min, 2) -65 to -40 deg C, overnight View Scheme

1: 100 percent / NaBH4 / tetrahydrofuran; aq. ethanol / 1.25 h / 0 - 5 °C 2: 1) lithium diisopropylamide / 1) THF, hexane, a) -75 deg C, 90 min, b) rt, 30 min, 2) -65 to -40 deg C, overnight View Scheme

1: 1) n-Bu4NHSO4, NaOH / 1) CH2Cl2, 0 deg C, 2) CH2Cl2, 0 - 5 deg C, 25 min 2: 100 percent / NaBH4 / tetrahydrofuran; aq. ethanol / 1.25 h / 0 - 5 °C 3: 1) lithium diisopropylamide / 1) THF, hexane, a) -75 deg C, 90 min, b) rt, 30 min, 2) -65 to -40 deg C, overnight View Scheme

1: tert-butyllithium / tetrahydrofuran / -40 - 23 °C 2: tetrahydrofuran / -70 °C View Scheme

in tetrahydrofuran T=-70°C;

lithium diisopropyl amide 1) THF, hexane, a) -75 deg C, 90 min, b) rt, 30 min, 2) -65 to -40 deg C, overnight; Yield given. Multistep reaction;

potassium fluoride; hydroquinone in acetic acid T=100°C; 3 h;