potassium carbonate in N,N-dimethyl-formamide T=65°C; 36 h;

1: 80 percent / KOH / tetrahydrofuran; H2O; methanol / 12 h 2: 1.) oxalyl chloride, DMF, 2.) triethylamine / 1.) CH2Cl2, reflux, 40 min, 2.) THF, 0 deg C, 30 min 3: 1.) Na2S2SO4, 2.) aq. HCl / 1.) THF, H2O, room temp., 1.5 d, 2.) THF, H2O, room temp., 2 d 4: 89 percent / H2 / Pd/C / methanol / 5 h / 60 °C / 2068.6 Torr 5: 79.4 percent / 24 h / Heating 6: 70 percent / oxalyl chloride, DMSO / CH2Cl2 / 1 h / -78 °C 7: 90 percent / pyridine / CH2Cl2 / 3 h / Ambient temperature 8: 50 percent / DABCO / (CH3CN)2PdCl2 / methanol / 45 °C 9: 99 percent / NaBH4 / methanol / 4.5 h 10: 0.1 M aq. HCl / 2 h / Ambient temperature View Scheme