Ethanol → 4-Bromo-5-fluoro-1,2-benzenediamine

Beteiligte Stoffe

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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).

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