1: 28 percent / PPh3, diethyl azodicarboxylate (DEAD) / benzene / 48 h / Ambient temperature 2: 84 percent / tetrabutylammonium fluoride / tetrahydrofuran / 0.05 h / Ambient temperature 3: 49 percent / 3 N aq. HCl / tetrahydrofuran / 18 h / Ambient temperature View Scheme

Multi-step reaction with 3 steps 1: 78.4 percent / diisopropylethylamine, 4-(dimethylamino)pyridine / CH2Cl2 / 3 h / 0 - 20 °C2: 1.) sodium bis(trimethylsilyl)amide, hexamethylphosphoric triamide (HMPA) / 1.) THF, -78 deg C, 30 min, 2.) THF, 30 min3: 89.3 percent / pyridine*(HF)x / tetrahydrofuran / 1 h / 0 °C  

Multi-step reaction with 9 steps 1: 72.5 percent / 2 N aq. HCl / tetrahydrofuran / 24 h / Ambient temperature2: 74.6 percent / camphorsulfonic acid / toluene / 4.5 h / Ambient temperature3: 93 percent / imidazole, 4-(dimethylamino)pyridine / dimethylformamide / 14 h / Ambient temperature4: 96.7 percent / LiAlH4 / tetrahydrofuran; diethyl ether / 0.08 h / 0 °C5: 1.) tert-butyllithium, 2.) O2 / 1.) THF, pentane, -78 deg C, 5 min6: 76.8 percent / Al2O3, pyridinium chlorochromate (PCC) / CH2Cl2 / 0.5 h / Ambient temperature7: 78.4 percent / diisopropylethylamine, 4-(dimethylamino)pyridine / CH2Cl2 / 3 h / 0 - 20 °C8: 1.) sodium bis(trimethylsilyl)amide, hexamethylphosphoric triamide (HMPA) / 1.) THF, -78 deg C, 30 min, 2.) THF, 30 min9: 89.3 percent / pyridine*(HF)x / tetrahydrofuran / 1 h / 0 °C