1: 95 percent / NaClO2, NaH2PO4*2H2O, 2-methyl-2-butene / 2-methyl-propan-2-ol; H2O / 0.5 h / Ambient temperature 2: Amberlyst-15 / methanol / 12 h / Ambient temperature 3: 85 percent / pyridine / 12 h / 70 °C 4: 0.3 N aq.LiOH / tetrahydrofuran / 120 h / 30 °C 5: benzenesulfonyl chloride, pyridine / 12 h / 0 °C 6: 5.4 mg / HOAc, H2O / 7 h / 50 °C View Scheme