1.1: trifluoroacetic anhydride / 24 h / |Inert atmosphere; |Reflux 2.1: ammonium cerium (IV) nitrate / acetonitrile; water; dichloromethane / 1 h / -40 - -20 °C / |Inert atmosphere 3.1: Yb(OTf)3-H2O / acetonitrile / 24 h / |Inert atmosphere 4.1: sodium hydride / tetrahydrofuran / 0.5 h / |Inert atmosphere 4.2: 4 h / -78 - 20 °C View Scheme

1.1: n-butyllithium; diisopropylamine / hexane; tetrahydrofuran / 0.25 h / -70 - -60 °C / |Inert atmosphere 1.2: 1 h / -40 °C / |Inert atmosphere 2.1: Yb(OTf)3-H2O / acetonitrile / 24 h / |Inert atmosphere 3.1: sodium hydride / tetrahydrofuran / 0.5 h / |Inert atmosphere 3.2: 4 h / -78 - 20 °C View Scheme

1.1: trifluoroacetic anhydride / 24 h / |Inert atmosphere; |Reflux 2.1: ammonium cerium (IV) nitrate / acetonitrile; water; dichloromethane / 1 h / -40 - -20 °C / |Inert atmosphere 3.1: Yb(OTf)3-H2O / acetonitrile / 24 h / |Inert atmosphere 4.1: sodium hydride / tetrahydrofuran / 0.5 h / |Inert atmosphere 4.2: 4 h / -78 - 20 °C View Scheme

1.1: Yb(OTf)3-H2O / acetonitrile / 24 h / |Inert atmosphere 2.1: sodium hydride / tetrahydrofuran / 0.5 h / |Inert atmosphere 2.2: 4 h / -78 - 20 °C View Scheme

1: 81 percent / HBr / acetic acid / 9 h / 45 - 50 °C 2: 100 percent / dioxane; H2O / 10 h / Heating 3: 73 percent / aq. KOH / methanol / 22 h / Heating 4: 63 percent / PPA / 1.5 h / 60 - 70 °C 5: 1.) NBS, dibenzoyl peroxide, 2.) H2O / 1.) CCl4, reflux, 4.5 h 6: 74 percent / PCC, Celite / CH2Cl2 / 3 h / 25 °C 7: 69 percent / AlCl3 / CH2Cl2 / 4 h / 55 °C 8: 1.) Me3SiI, 2.) MeOH / 1.) CDCl3, 25 deg C, 27 h 9: p-TsOH / benzene / 5 h / Heating View Scheme

1: 1.) Na2S2O4, n-tetrabutylammonium bromide, 2.) KOH / 1.) aq. THF 2: 87 percent / TFAA, TFA / 12 h / 60 °C 3: 95 percent / Et3SiH / trifluoroacetic acid / 6 h / 25 °C 4: 81 percent / HBr / acetic acid / 9 h / 45 - 50 °C 5: 100 percent / dioxane; H2O / 10 h / Heating 6: 73 percent / aq. KOH / methanol / 22 h / Heating 7: 63 percent / PPA / 1.5 h / 60 - 70 °C 8: 1.) NBS, dibenzoyl peroxide, 2.) H2O / 1.) CCl4, reflux, 4.5 h 9: 74 percent / PCC, Celite / CH2Cl2 / 3 h / 25 °C 10: 69 percent / AlCl3 / CH2Cl2 / 4 h / 55 °C 11: 1.) Me3SiI, 2.) MeOH / 1.) CDCl3, 25 deg C, 27 h 12: p-TsOH / benzene / 5 h / Heating View Scheme