1: 1.) (COCl)2, DMSO, 2.) Et3N 2: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 3: 75 percent / toluene / 36 h / 200 °C 4: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 5: 72 percent / NaBH4, CeCl3 / ethanol 6: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 7: 81 percent / (MeO)3BF4 8: 79 percent / ethanol. NaOEt 9: 99 percent / imidazole / dimethylformamide 10: 75 percent / tetrahydrofuran / Ambient temperature 11: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 12: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 13: 90 percent / m-CPBA, NaHCO3 14: 70 percent / BF3*Et2O / -78 - 20 °C 15: NH2OH*HCl, NaOAc / ethanol 16: carbonyldiimidazole / CH2Cl2 / Ambient temperature 17: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 18: 2.) H2O / 1.) THF, -78 deg C 19: 96 percent / H2 / 10percent Pd/C / ethanol 20: 74 percent / Et3N / benzene 21: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme