3,5-Dibromo-4-hydroxybenzoic acid → Ethyl 5-(3,5-dibromo-4-hydroxyphenyl)-1,2,4-oxadiazole-3-carboxylate

HRID 2402271Notes

Reaction equation

HRID 2402271 reaction equation
Cl.CN(C)CCCN=C=NCC.[NH2:13][C:14](=[N:20][OH:21])[C:15]([O:17][CH2:18][CH3:19])=[O:16].[Br:22][C:23]1[CH:24]=[C:25]([CH:29]=[C:30]([Br:33])[C:31]=1[OH:32])[C:26](O)=O>N1C=CC=CC=1>[Br:22][C:23]1[CH:24]=[C:25]([C:26]2[O:21][N:20]=[C:14]([C:15]([O:17][CH2:18][CH3:19])=[O:16])[N:13]=2)[CH:29]=[C:30]([Br:33])[C:31]=1[OH:32]

Participants

5

Reactant 3

HCID 768573,5-Dibromo-4-hydroxybenzoic acidHCID 27239391,3-Propanediamine, N'-(ethylcarbonimidoyl)-N,N-dimethyl-, monohydrochlorideHCID 6785548Ethyl 2-amino-2-(hydroxyimino)acetate

Product 1

HCID 136139578Ethyl 5-(3,5-dibromo-4-hydroxyphenyl)-1,2,4-oxadiazole-3-carboxylateYield 12.2%

Reagents, catalysts & solvents 1

HCID 1049PyridineSolvent

Procedure

N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (1.32 g, 10 mmol) was added in one portion to a stirred solution of ethyl 2-amino-2-(hydroxyimino)acetate (1.32 g, 10 mmol) plus 3,5-dibromo-4-hydroxybenzoic acid (2.95 g, 10 mmol) in pyridine (20 mL), the resulting solution was stirred at room temperature for 2 h and then at 90° C. for 5 h. After standing at room temperature overnight the pyridine was evaporated in vacuo and the residue was purified by flash chromatography (silica gel, 10% ethyl acetate/dichloromethane) to give the title compound (0.48 g, 12%) as a colourless solid. 1H NMR δ (ppm) (DMSO-d6): 1.48 (3 H, t), 4.47 (2 H, d), 8.13 (2 H, s), 11.54 (1 H, s, br).

Workup

  1. waitat 90° C. for 5 h
  2. waitAfter standing at room temperature overnight
  3. customthe pyridine was evaporated in vacuo
  4. customthe residue was purified by flash chromatography (silica gel, 10% ethyl acetate/dichloromethane)

Sources & evidence

ORD record
ord-747478564879444e9c9ce8bd52c427ea
Source dataset
uspto-grants-2014_08
Patent number
US08796321B2

Reaction notes

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