3,4,5-Trichlorobenzene-1,2-diamine → 2-Amino-4,5,6-trichlorobenzimidazole

To a stirred solution of 3.62 mL of 5M BrCN/MeCN in 35 mL of H2O, was added dropwise a solution of 3,4,5-trichloro-1,2-phenylenediamine (13a) (3.478 g, 16.446 mmol) in 35 mL of MeOH, After the addition had been completed, stirring was continued at room temperature for 2 hr. The reaction mixture was concentrated to ~ 35 mL and was washed with EtOAc (50 mL). The EtOAc phase was extracted with H2O (50 mL). The combined H2O phase was neutralized with sat. NaHCO3 solution to ~ pH 8 and the resulting suspension was extracted with EtOAc (150 mL). The EtOAc phase was washed with a mixture of sat. NaHCO3 and sat. NaCl solution (20 mL/130 mL), dried (Na2SO4), and evaporated. The residue was dissolved in MeOH, decolorized with charcoal, and then recrystallized from MeCN to give 3.098 g (2 crops, 80%) of 13b as a slightly grey crystals. MP: 255°-258° C. MS: (EI) m/e 234.9473 (100%, M+ =234.9471). 1H NMR (DMSO-d6): d 11.25 (br s, 1, 1-NH), 7.29 {s, 1, 7(4)-H}, 6.75 (br s, 2, 2-NH2). Anal. Calcd. for C7H4Cl3N3 : C 35.55, H 1.70, N 17.77, Found: C 35.72, H 1.78, N 17.89.

1. additionAfter the addition
2. concentrationThe reaction mixture was concentrated to ~ 35 mL
3. washwas washed with EtOAc (50 mL)
4. extractionThe EtOAc phase was extracted with H2O (50 mL)
5. extractionthe resulting suspension was extracted with EtOAc (150 mL)
6. washThe EtOAc phase was washed with a mixture of sat. NaHCO3 and sat. NaCl solution (20 mL/130 mL)
7. dry with materialdried (Na2SO4)
8. customevaporated
9. dissolutionThe residue was dissolved in MeOH
10. customrecrystallized from MeCN

ORD record

ord-54e436ea9e2249ddb6639585b35f4a42

Source dataset

uspto-grants-1996_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05574058