1: 1) KH / 1) THF, mineral oil, r.t., 15 min, 2) THF, 40 deg C, 2 d 2: 75 percent / 1 M tetra(n-butyl)ammonium fluoride / tetrahydrofuran / 3 h / 0 °C 3: 1a) oxalyl chloride, DMSO, 2) Et3N / 1a) CH2Cl2, -78 deg C, 15 min, b) -78 deg C, 1 h, 2) -78 to 0 deg C 4: 95 percent / NaClO2, NaH2PO4*2H2O, 2-methyl-2-butene / 2-methyl-propan-2-ol; H2O / 0.5 h / Ambient temperature 5: Amberlyst-15 / methanol / 12 h / Ambient temperature 6: 85 percent / pyridine / 12 h / 70 °C 7: 0.3 N aq.LiOH / tetrahydrofuran / 120 h / 30 °C 8: benzenesulfonyl chloride, pyridine / 12 h / 0 °C 9: 5.4 mg / HOAc, H2O / 7 h / 50 °C View Scheme

1: 75 percent / 1 M tetra(n-butyl)ammonium fluoride / tetrahydrofuran / 3 h / 0 °C 2: 1a) oxalyl chloride, DMSO, 2) Et3N / 1a) CH2Cl2, -78 deg C, 15 min, b) -78 deg C, 1 h, 2) -78 to 0 deg C 3: 95 percent / NaClO2, NaH2PO4*2H2O, 2-methyl-2-butene / 2-methyl-propan-2-ol; H2O / 0.5 h / Ambient temperature 4: Amberlyst-15 / methanol / 12 h / Ambient temperature 5: 85 percent / pyridine / 12 h / 70 °C 6: 0.3 N aq.LiOH / tetrahydrofuran / 120 h / 30 °C 7: benzenesulfonyl chloride, pyridine / 12 h / 0 °C 8: 5.4 mg / HOAc, H2O / 7 h / 50 °C View Scheme

1: 0.3 N aq.LiOH / tetrahydrofuran / 120 h / 30 °C 2: benzenesulfonyl chloride, pyridine / 12 h / 0 °C 3: 5.4 mg / HOAc, H2O / 7 h / 50 °C View Scheme

1: benzenesulfonyl chloride, pyridine / 12 h / 0 °C 2: 5.4 mg / HOAc, H2O / 7 h / 50 °C View Scheme