Reacción #82571

Ecuación de reacción

NaHCO3

2-bromo-3,4-difluoro-6-nitroaniline

SnCl2.2H2O

ethanol

→

3-Bromo-4,5-difluoro-1,2-diaminobenzene

Disolventes

—

hexanes

ethyl acetate

ethyl acetate

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroAll the starting material had reacted
2. 2
   workup.ADDITIONpoured into 20 mL
3. 3
   Otrocrushed ice
4. 4
   workup.ADDITIONwas added (foaming!)
5. 5
   ExtracciónThe thick yellow white emulsion was then extracted with 3×25 mL ethyl acetate
6. 6
   Lavadothe combined organic extracts washed with sat'd NaCl solution
7. 7
   SecadoThe organic phase was dried (MgSO4), vacuum
8. 8
   Filtraciónfiltered
9. 9
   Otrothe solvent rotary evaporated
10. 10
    Otroto yield a dark brown oil which
11. 11
    Otrocrystallized
12. 12
    Otroto yield 410 mg (66%)

Procedimiento

3-Bromo-4,5-difluoro-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 2-bromo-3,4-difluoro-6-nitroaniline (700 mg, 2.78 mmol) and SnCl2.2H2O (3.14 g, 13.9 mmol) dissolved in 7 mL ethyl acetate and 3 mL absolute ethanol under N2 was heated at 75° C. for 2 h. All the starting material had reacted as evidenced by TLC (silica gel, 2:1 hexanes:ethyl acetate). The reaction was allowed to cool to room temperature and poured into 20 mL crushed ice. Sufficient sat'd NaHCO3 solution was added (foaming!) to bring the pH to 5. The thick yellow white emulsion was then extracted with 3×25 mL ethyl acetate and the combined organic extracts washed with sat'd NaCl solution. The organic phase was dried (MgSO4), vacuum filtered and the solvent rotary evaporated to yield a dark brown oil which crystallized on standing to yield 410 mg (66%). 1H NMR (CDCl3) δ3.59 (br s, 4H, 2(NH2)); 6.52 (m, 1H, H-6).

Fuente