1: 2.) Bu4NF / 1.) THF, 0-5 deg C, 3 h, 2.) THF, 0 deg C, 2 h 2: 96 percent / Zn/Ag / tetrahydrofuran; ethanol; diethyl ether / 12 h / 45 °C 3: 4-(dimethylamino)pyridine, pyridine / 2.5 h 4: HOAc, H2O / tetrahydrofuran / 168 h / 50 °C View Scheme

Multi-step reaction with 4 steps 1: 61 percent / tetrahydrofuran / 1 h / Heating2: 96 percent / Bu4NF / tetrahydrofuran / 1 h / 0 °C3: Na2HPO4, m-chloroperoxybenzoic acid / CH2Cl2 / 3 h / 23 °C4: Zn/Ag / diethyl ether; tetrahydrofuran; ethanol / 18 h / 50 - 55 °C