1: 85 percent / TsOH / 1,2-dimethoxy-ethane / 4 h 2: 85 percent / LHMDS / tetrahydrofuran / -78 °C 3: dicyclohexylcarbodiimide; DMSO; CF3COOH / pyridine 4: 60 percent / TiCl4 / -78 - 35 °C 5: O3; Me2S 6: NaClO2; NaH2PO4 7: HCOONH4 / Pd black 8: NaOH; H2O 9: bis(2-oxo-3-oxazolidinyl)phosphonic chloride View Scheme

1: 85 percent / TsOH / 1,2-dimethoxy-ethane / 4 h 2: 85 percent / LHMDS / tetrahydrofuran / -78 °C 3: dicyclohexylcarbodiimide; DMSO; CF3COOH / pyridine 4: 60 percent / TiCl4 / -78 - 35 °C 5: O3; Me2S 6: NaClO2; NaH2PO4 7: HCOONH4 / Pd black 8: NaOH; H2O View Scheme