1: 1.) NaH / 1.) DMF, RT, 2.) DMF, RT, 1 h 2: aq. Ba(OH)2 / ethanol / 0.33 h / 70 °C 3: 170 °C 4: 89.2 percent / LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 5: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 6: tetrahydrofuran / 1 h / 0 - 5 °C 7: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 8: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 9: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: tetrahydrofuran / 1 h / 0 - 5 °C 2: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 3: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 4: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 2: tetrahydrofuran / 1 h / 0 - 5 °C 3: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 4: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 5: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 2: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: 170 °C 2: 89.2 percent / LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 3: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 4: tetrahydrofuran / 1 h / 0 - 5 °C 5: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 6: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 7: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: aq. Ba(OH)2 / ethanol / 0.33 h / 70 °C 2: 170 °C 3: 89.2 percent / LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 4: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 5: tetrahydrofuran / 1 h / 0 - 5 °C 6: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 7: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 8: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: 89.2 percent / LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 2: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 3: tetrahydrofuran / 1 h / 0 - 5 °C 4: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 5: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 6: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 2: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 3: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme

1: 1.) EtONa / 1.) EtOH, RT, 2.) EtOH, reflux, 24 h 2: 1.) NaH / 1.) DMF, RT, 2.) DMF, RT, 1 h 3: aq. Ba(OH)2 / ethanol / 0.33 h / 70 °C 4: 170 °C 5: 89.2 percent / LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 6: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 7: tetrahydrofuran / 1 h / 0 - 5 °C 8: trifluoroacetic anhydride, DMSO / CH2Cl2 / 1.5 h / -60 °C 9: LiB(Et)3H / tetrahydrofuran / 1 h / 0 °C 10: 1.) LDA, HMPT, 2.) P(OEt)3, O2 / 1.) THF, hexane, from -70 to -60 deg C, 1 h, 2.) THF, hexane, -70 deg C View Scheme