1: imidazole / dimethylformamide 2: 95 percent / NaBH4 / methanol / 0.5 h / -5 °C 3: DMAP, pyridine / CH2Cl2 4: N,O-bis-trimethylsilyl acetamide / SnCl4 / 3 h / -15 °C 5: 41 percent / TBAF / tetrahydrofuran 6: H2 / Pd-C / ethanol; H2O View Scheme