1: imidazole / dimethylformamide / 40 °C 2: 93 percent / imidazole / dimethylformamide / 40 °C 3: 91 percent / 1N HCl / methanol / 0 °C 4: hexamethyldisilazane / pyridine 5: trimethylsilyl triflate, Et3N / CH2Cl2 / 24 h / 40 °C 6: 1N HCl / methanol / 0.17 h / 0 °C 7: 92 percent / pyridinium dichromate / dimethylformamide / Ambient temperature View Scheme