1: 94 percent / Et3N / tetrahydrofuran; acetonitrile / 20 °C 2: 60 percent / KHCO3 / dimethylformamide / 264 h 3: 80 percent / NaOH / H2O; tetrahydrofuran 4: 90 percent / H2 / Pd(OH)2/C View Scheme