Cyanogen Bromide → 5,6-difluoro-1H-1,3-benzodiazol-2-amine

HRID 907718Notes

Reaction equation

HRID 907718 reaction equation
[NH2:1][C:2]1[CH:7]=[C:6]([F:8])[C:5]([F:9])=[CH:4][C:3]=1[NH2:10].[N:11]#[C:12]Br.C(=O)(O)[O-].[Na+]>O>[F:8][C:6]1[C:5]([F:9])=[CH:4][C:3]2[NH:10][C:12]([NH2:11])=[N:1][C:2]=2[CH:7]=1

Participants

5

Reactant 3

HCID 10476Cyanogen BromideHCID 516892Sodium BicarbonateHCID 27367551,2-Diamino-4,5-difluorobenzene

Product 1

HCID 106787085,6-difluoro-1H-1,3-benzodiazol-2-amineYield 98.8%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

The procedure used was similar to that reported in J. Med. Chem. 40:811-818, 1997. A solution of 1,2-diamino-4,5-difluorobenzene (500 mg, 3.47 mmol) in water (5 mL) was cooled to 0° C. and then treated with a solution of cyanogen bromide (0.83 mL, 4.16 mmol, 5 M in acetonitrile) and solid sodium bicarbonate (583 mg, 6.94 mmol). The solution was stirred at rt overnight and was then concentrated in vacuo. The dark residue was suspended in ethanol and heated at reflux for 15 minutes. The hot suspension was filtered, rinsing with hot ethanol, and the filtrate was concentrated in vacuo to afford 5,6-difluoro-1H-benzimidazol-2-amine (580 mg, 59%), which was used in the next step without further purification. LC-MS m/z 170.2 (MH+), ret. time 0.85 min; 1H NMR (300 MHz, DMSO-d6) δ 6.30 (br s, 2H), 7.06 (dd, 2H), 10.79 (br s, 1H).

Workup

  1. concentrationwas then concentrated in vacuo
  2. temperatureheated
  3. temperatureat reflux for 15 minutes
  4. filtrationThe hot suspension was filtered
  5. washrinsing with hot ethanol
  6. concentrationthe filtrate was concentrated in vacuo

Sources & evidence

ORD record
ord-465fd2d882a746df95e895474cfd3220
Source dataset
uspto-grants-2011_09
Patent number
US08013166B2

Reaction notes

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