1: pyridine / dimethylformamide / 18 h / 20 °C 2: 0.52 g / aq. HCl / tetrahydrofuran / 12 h / 20 °C 3: 85 percent / tetramethylurea; AgOTf / CH2Cl2 / 12 h / 20 °C 4: 52 percent / copper(II) acetate; lithium acetate; palladium(II) acetate / dimethylformamide / 1 h / 100 °C 5: 86 percent / NaOMe / methanol; tetrahydrofuran / 1 h / 20 °C View Scheme