1: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 2: 75 percent / toluene / 36 h / 200 °C 3: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 4: 72 percent / NaBH4, CeCl3 / ethanol 5: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 6: 81 percent / (MeO)3BF4 7: 79 percent / ethanol. NaOEt 8: 99 percent / imidazole / dimethylformamide 9: 75 percent / tetrahydrofuran / Ambient temperature 10: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 11: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 12: 90 percent / m-CPBA, NaHCO3 13: 70 percent / BF3*Et2O / -78 - 20 °C 14: NH2OH*HCl, NaOAc / ethanol 15: carbonyldiimidazole / CH2Cl2 / Ambient temperature 16: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 17: 2.) H2O / 1.) THF, -78 deg C 18: 96 percent / H2 / 10percent Pd/C / ethanol 19: 74 percent / Et3N / benzene 20: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme