1,2-Diamino-4,5-difluorobenzene → 5,6-difluoro-1H-1,3-benzodiazol-2-amine

Participants

Reaction Steps

To a stirred solution of 4.9 mL of 5M BrCN/MeCN in 50 mL of H2O, was added dropwise a solution of 3.515 g (24.389 mmole) of 10 in 50 mL of MeOH over 20 min. After the addition, stirring was continued at room temperature for 2 h. The reaction mixture was concentrated to ~ 50 mL and was extracted with EtOAc (50 mL×3). The combined EtOAc solution was back washed with 100 mL of H2O and then discarded. The combined H2O phase was basified with sat. NaHCO3 solution (precipitation occurred) and was extracted again with EtOAc (70 mL×3). The EtOAc solution was dried (Na2SO4) and evaporated to dryness. The residue was suspended in 50 mL of CHCl3 and filtered. The yellowish solid was washed with portions of CHCl3 to give 3.40 g of 11. The filtrate and washings were evaporated to dryness and the procedure was repeated to give an additional 0.355 g of 11. The total yield of 11 was 3.755 g (91%). 1H NMR (DMSO-d6) d 10.79 (br. s, 1, 1-NH), 7.06 (dd, 2, 4-H and 7-H, 3JF-H =11.0 Hz, 4JF-H =7.5 Hz), 6.30 (br. s, 2, 2-NH2).

Provenance & Evidence