1: 50 percent / HMPA, LiHMDS / tetrahydrofuran / 0.17 h / -78 °C 2: 92 percent / PPTS / methanol; CH2Cl2 / 2 h / 40 °C 3: 94 percent / K2CO3 / aq. ethanol / 0.5 h / 125 °C 4: 68 percent / PCC on alumina / CH2Cl2; hexane / 15 h / Ambient temperature View Scheme

Multi-step reaction with 2 steps 1: 50 percent / HMPA, LiHMDS / tetrahydrofuran / 0.17 h / -78 °C2: 92 percent / PPTS / methanol; CH2Cl2 / 2 h / 40 °C