2: 1.) O3, 2.) NaBH4 / 1.) CH2Cl2, MeOH, -78 deg C, 2.) -> r.t., overnight 3: pyridine, 4-(N,N-dimethylamino)pyridine / 2 h / 0 °C 4: diisopropylethylamine / CH2Cl2 / 0.5 h / 0 °C 5: LiEt3BH / tetrahydrofuran / 1.17 h / Heating 6: (COCl)2, DMSO 7: potassium tert-butoxide / tetrahydrofuran / -78 deg C -> r.t. 8: 1.) Cp2ZrCl2, 2.) I2 / 1.) dichloroethane, 23,5 h, 2.)THF, -25 deg C to -10 deg C, 140 min 9: 84 percent / Ag2CO3, triethylamine / Pd(OAc)2 / CH2Cl2; ethanol / 1.25 h 10: 1.) 2,2,6,6-tetramethyl-1-oxopiperidinium chloride, 2.) NaClO2, NaH2PO4*H2O / 1.) CH2Cl2, -20 deg C, 10 min, then -15 deg C, 2 h, 2.) 2-methylbutene, H2O 11: 70 percent / benzenesulfonyl chloride, pyridine / 18.5 h / 0 - 10 °C 12: 78 percent / aq. HF / tetrahydrofuran / 8.5 h View Scheme