1: 88 percent / H2 / Lindlar / methanol 2: 1.) DMSO, (COCl)2, Et3N, 2.) CSA / 1.) CH2Cl2, 2.) CH2Cl2, room temperature 3: 23 percent / (C6H11)2NMgBr / tetrahydrofuran / -55 °C 4: 95 percent / DDQ / CH2Cl2; H2O / 0.17 h / Ambient temperature 5: 70 percent / TFA, molecular sieves / CH2Cl2 View Scheme