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 (213 mL/130 mL), dried (Na2 SO4), 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: (El) 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 (213 mL/130 mL)
7. customdried (Na2 SO4)
8. customevaporated
9. dissolutionThe residue was dissolved in MeOH
10. customrecrystallized from MeCN

ORD record

ord-644ee71560c04f65973de7f05c69f481

Source dataset

uspto-grants-1998_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05705490