1: Na, NH3(l) / 0.08 h 2: pyridine / 4 h / 0 °C 3: i-Pr2NEt / CH2Cl2 / 1 h / 0 °C 4: MeLi / CH2Cl2 / 4 h / -78 °C 5: 1) (COCl)2, DMSO 2) Et3N / 1) CH2Cl2, -78 to -40 deg C 6: NaClO2, NaH2PO4, 2-methyl-2-butene / 2-methyl-propan-2-ol / 0.5 h / 0 to 20 deg C 7: 66 percent / HOBT, 1-(3-dimethylaminopropyl)-ethylcarbodiimide*HCl / CH2Cl2; dimethylformamide / 10 h / 0 to 20 deg C 8: 54 percent / TBAF / tetrahydrofuran / 1.5 h / 20 °C View Scheme