trifluoroacetic acid in water 2 h; Ambient temperature;

1: CF3COOH / H2O / 2 h / Ambient temperature 2: imidazole / dimethylformamide / 3 h / Ambient temperature View Scheme

1: CF3COOH / H2O / 2 h / Ambient temperature 2: imidazole / dimethylformamide / 3 h / Ambient temperature 3: 90.4 percent / DIBAL / toluene / 0.25 h / -78 °C 4: 62 percent / AcOH / tetrahydrofuran; H2O / 24 h / 60 - 70 °C View Scheme

1: CF3COOH / H2O / 2 h / Ambient temperature 2: imidazole / dimethylformamide / 3 h / Ambient temperature 3: 90.4 percent / DIBAL / toluene / 0.25 h / -78 °C 4: 62 percent / AcOH / tetrahydrofuran; H2O / 24 h / 60 - 70 °C View Scheme

1: CF3COOH / H2O / 2 h / Ambient temperature 2: imidazole / dimethylformamide / 3 h / Ambient temperature 3: 90.4 percent / DIBAL / toluene / 0.25 h / -78 °C 4: 62 percent / AcOH / tetrahydrofuran; H2O / 24 h / 60 - 70 °C View Scheme