Boron tribromide → 2-Amino-4-hydroxybenzamide

HRID 625772Notes

Reaction equation

HRID 625772 reaction equation
[NH2:1][C:2]1[CH:10]=[C:9]([O:11]C)[CH:8]=[CH:7][C:3]=1[C:4]([NH2:6])=[O:5].B(Br)(Br)Br>ClCCCl.C1COCC1>[NH2:1][C:2]1[CH:10]=[C:9]([OH:11])[CH:8]=[CH:7][C:3]=1[C:4]([NH2:6])=[O:5]

Participants

5

Reactant 2

HCID 25134Boron tribromide2×HCID 140230022-Amino-4-methoxybenzamide

Product 1

HCID 205014282-Amino-4-hydroxybenzamideYield 31.3%

Reagents, catalysts & solvents 2

HCID 111,2-DichloroethaneSolventHCID 8028TetrahydrofuranSolvent

Conditions

Temperature
40 °C

Procedure

To 2-amino-4-methoxybenzamide (7.0 g, 42 mmol) in 1,2-dichloroethane (100 mL) was added boron tribromide (25 g, 100 mmol) at rt. After heating for 40° C. for 20 h, 1 N boron tribromide in THF (40 mL) was added, and the reaction was heated to 50° C. for 20 h. The mixture was cooled and quenched by addition of aq. sodium bicarbonate. The resulting precipitate was collected by filtration to afford 2-amino-4-hydroxybenzamide as a white solid (2.0 g). The mother liquors were concentrated, diluted with MeOH., filtered and concentrated. The residue was again diluted with MeOH, filtered and concentrated, and the resulting residue was chromatographed on silica gel eluting with 5-15% MeOH/DCM to give 2-amino-4-hydroxybenzamide as a white solid (4.7 grams). The solids were combined for a total yield of 6.7 g (quantitative). 1H NMR (300 MHz, DMSO-d6) δ ppm 5.91 (dd, J=8.67, 2.26 Hz, 1H) 6.03 (d, J=2.45 Hz, 1H) 6.62 (br. s., 2H) 7.38 (d, J=8.67 Hz, 1H) 9.45 (s, 1H). LC-MS (ESI) m/z 153 (M+H)+.

Workup

  1. temperaturethe reaction was heated to 50° C. for 20 h
  2. temperatureThe mixture was cooled
  3. customquenched by addition of aq. sodium bicarbonate
  4. filtrationThe resulting precipitate was collected by filtration

Sources & evidence

ORD record
ord-71a060b2b28e40cfa7c5e5f331fc07d4
Source dataset
uspto-grants-2016_04
Patent number
US09308207B2

Reaction notes

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