1.1: 53 percent / ammonium hydroxide / 24 h / 130 °C 2.1: lithium hexamethyldisilazane / dimethylformamide; tetrahydrofuran / 0.17 h / -10 °C 2.2: 41 percent / Ph2P(O)ONH2 / tetrahydrofuran; dimethylformamide / 20 °C 3.1: 52 percent / pyridine / 2 h / 60 °C 4.1: 72 percent / KOtBu / 2-methyl-propan-2-ol / 30 h / 160 °C View Scheme