hydrogen; platinum(IV) oxide in diethyl ether T=4°C;

Multi-step reaction with 5 steps 1: 1.) n-BuLi / 1.) THF, hexane, -78 deg C, 1 h, 2.) THF, hexane, a) -20 deg C, 3 h, b) from -78 deg C to RT, 1 h2: 1.) CuI / 1.) ether, hexane, 2.) ether, hexane, -20 deg C, 3 h3: 79 percent / DDQ, H2O / CH2Cl2 / 3 h / Ambient temperature4: 1.) (COCl)2, DMSO, 2.) Et3N / 1.) CH2Cl2, -78 deg C, 2 h, 2.) CH2Cl2, from -78 deg C to RT, 1 h5: 88 percent / MnO2, NaCN, AcOH / 3 h / Ambient temperature