[Br:1][C:2]1[CH:8]=[C:7]([N+:9]([O-])=O)[C:5]([NH2:6])=[CH:4][C:3]=1[F:12].Cl[Sn]Cl.C(O)C.C([O-])(O)=O.[Na+]>C(OCC)(=O)C.O>[Br:1][C:2]1[C:3]([F:12])=[CH:4][C:5]([NH2:6])=[C:7]([NH2:9])[CH:8]=1
4-Bromo-5-fluoro-1,2-diaminobenzene was prepared using an adaptation of the method of Bellamy et al. (Bellamy, F. D. et al., Tetrahedron Lett. 25:839 (1984)). A mixture of 4-bromo-3-fluoro-6-nitroaniline (320 mg, 1.36 mmol) and SnCl2 °2H2O (1.53 g, 6.81 mmol) dissolved in 7 mL ethyl acetate and 3 mL absolute ethanol under N2 was heated at 75° C. for 8 h. Some starting material had remained (by TLC) after only 1 h heating. All the starting material had reacted after 8 h as evidenced by TLC (silica gel, 3:1 hexanes:ethyl acetate). The reaction was allowed to cool to room temperature and poured into 50 mL H2O. Sufficient sat'd NaHCO3 solution was added (foaming ) to bring the pH to 5. The resulting mixture was extracted with 3×25 mL ethyl acetate and the combined organic extracts washed with 20 mL sat'd NaCl solution. The organic phase was dried (MgSO4), vacuum filtered and the solvent rotary evaporated to yield a white powder 277 mg (99%). 1H NMR (CDCl3) δ3.22 (br s, 2H, NH2); 3.60 (br s, 2H, NH2); 6.50 (d, 1H, JHF =9.6 Hz, H-6); 6.83 (d, 1H, JHF =6.6 Hz, H-3).
Loading…
