1: 95 percent / 1,3-dicyclohexylcarbodiimide (DCC), 4-(dimethylamino)pyridine (DMAP), camphorsulfonic acid (CSA) / CH2Cl2 / 4 h / 25 °C 2: 89 percent / HF, pyridine / tetrahydrofuran / 0 °C 3: 93 percent / H2 / 10percent Pd(OH)2/C / ethyl acetate / 2 h / Ambient temperature 4: 45 percent / triphenylphosphine, 2,2'-dipyridyl disulfide / toluene / 1.) 25 deg C, 3 h, 2.) reflux, 12 h View Scheme

1: 92 percent / imidazole / dimethylformamide 2: 95 percent / H2 / 5 percent Pd/C 3: DMAP; DCC / CH2Cl2 / 24 h / 20 °C 4: TBAF / tetrahydrofuran / 48 °C View Scheme

1: 92 percent / imidazole / dimethylformamide 2: 95 percent / H2 / 5 percent Pd/C View Scheme

2,6-dimethylpyridine; tetraethylammonium bromide; Xtalfluor-E® in dichloromethane T=21°C; Inert atmosphere;