1: 83 percent / SOCl2; pyridine / acetonitrile 2: 94 percent / Et3N / tetrahydrofuran; acetonitrile / 20 °C 3: 60 percent / KHCO3 / dimethylformamide / 264 h 4: 80 percent / NaOH / H2O; tetrahydrofuran 5: 90 percent / H2 / Pd(OH)2/C View Scheme

hydrogenchloride; orthoformic acid triethyl ester in N,N-dimethyl-formamide 168 h; Ambient temperature;