1.1: LDA / tetrahydrofuran / 1 h / -50 °C 1.2: 75 percent / tetrahydrofuran; hexamethylphosphoric acid triamide / 3 h / -50 - 0 °C 2.1: LiOH; H2O / tetrahydrofuran; methanol / 12 h / 0 - 20 °C 3.1: 210 mg / PhSO2Cl; pyridine / 12 h / 0 °C 4.1: 88 percent / BF3*Et2O; ethane-1,2-dithiol / CH2Cl2 / 1 h / 0 °C View Scheme

1.1: LDA / tetrahydrofuran / 1 h / -50 °C 1.2: 75 percent / tetrahydrofuran; hexamethylphosphoric acid triamide / 3 h / -50 - 0 °C 2.1: LiOH; H2O / tetrahydrofuran; methanol / 12 h / 0 - 20 °C 3.1: 210 mg / PhSO2Cl; pyridine / 12 h / 0 °C 4.1: 88 percent / BF3*Et2O; ethane-1,2-dithiol / CH2Cl2 / 1 h / 0 °C 5.1: 90 percent / Ph3P; DIAD / tetrahydrofuran / 20 °C View Scheme

1.1: LDA / tetrahydrofuran / 1 h / -50 °C 1.2: 75 percent / tetrahydrofuran; hexamethylphosphoric acid triamide / 3 h / -50 - 0 °C 2.1: LiOH; H2O / tetrahydrofuran; methanol / 12 h / 0 - 20 °C 3.1: 210 mg / PhSO2Cl; pyridine / 12 h / 0 °C 4.1: 88 percent / BF3*Et2O; ethane-1,2-dithiol / CH2Cl2 / 1 h / 0 °C View Scheme