1.1: 83 percent / tetrahydrofuran / 5 h / -78 °C 2.1: 92 percent / KHCO3; KF; aq. H2O2 / methanol; tetrahydrofuran / 18 h / 23 °C 3.1: 83 percent / aq. ceric ammonium nitrate / acetonitrile / 1 h / 0 °C 4.1: aq. LiOH / tetrahydrofuran / 96 h / 5 °C 5.1: bis(2-oxo-3-oxazolidinyl)phosphonic chloride; pyridine / CH2Cl2 / 1 h / 23 °C 5.2: 100 mg / pyridine; PPh3Cl2 / acetonitrile; CH2Cl2 / 1 h / 23 °C View Scheme