1: 48 percent / HMPA, LiHMDS / tetrahydrofuran / 0.17 h / -78 °C 2: 50 percent / HMPA, LiHMDS / tetrahydrofuran / 0.17 h / -78 °C 3: 92 percent / PPTS / methanol; CH2Cl2 / 2 h / 40 °C 4: 94 percent / K2CO3 / aq. ethanol / 0.5 h / 125 °C 5: 68 percent / PCC on alumina / CH2Cl2; hexane / 15 h / Ambient temperature View Scheme

1: 1.) (i-Pr)2NH, 1.8 M BuLi/n-hexane / 1.) THF, 3 h, room temp., 2.) THF, 12 h, 55 deg C 2: 91 percent / Amberlyst H 15 / methanol / 1 h / 45 °C 3: KHSO4 / Heating View Scheme

Substitution;