1: 90 percent / p-TsOH / methanol / 2 h / Ambient temperature 2: 87 percent / pyridine / CH2Cl2 / 12 h / Ambient temperature 3: 90 percent / n-Bu4NF / tetrahydrofuran / 1.5 h / Ambient temperature 4: 96 percent / 1N aq.KOH / methanol / 0.17 h / Ambient temperature View Scheme