1: 62 percent / n-BuLi / tetrahydrofuran; hexane / 6 h / -70 °C 2: 99 percent / potassium azodicarboxylate, AcOH / methanol / 1 h / Ambient temperature 3: 0.1 N TFA / tetrahydrofuran / 4 h / Ambient temperature View Scheme