1: Et3N / tetrahydrofuran / 0.75 h / -78 - 0 °C 2: NaH / dimethylformamide / 0.75 h / 0 °C 3: 74 percent / TBAF / tetrahydrofuran / 2.5 h / 0 °C 4: (COCl)2; DMSO; (i-Pr)2NEt / CHCl3; hexane / 1.5 h / -78 - 0 °C 5: NaClO2; NaH2PO4*2H2O; 2-methylbut-2-ene / H2O; 2-methyl-propan-2-ol / 2 h / 20 °C View Scheme

1: Et3N / tetrahydrofuran / 0.75 h / -78 - 0 °C 2: NaH / dimethylformamide / 0.75 h / 0 °C 3: 74 percent / TBAF / tetrahydrofuran / 2.5 h / 0 °C 4: (COCl)2; DMSO; (i-Pr)2NEt / CHCl3; hexane / 1.5 h / -78 - 0 °C 5: NaClO2; NaH2PO4*2H2O; 2-methylbut-2-ene / H2O; 2-methyl-propan-2-ol / 2 h / 20 °C 6: diethyl ether / 0.5 h / 0 °C View Scheme