Ethoxalyl chloride → Ethyl 3-(3,5-dibromo-4-hydroxyphenyl)-1,2,4-oxadiazole-5-carboxylate

HRID 222353Notes

Reaction equation

HRID 222353 reaction equation
Cl[C:2](=[O:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4].[Br:9][C:10]1[CH:11]=[C:12]([CH:17]=[C:18]([Br:21])[C:19]=1[OH:20])[C:13](=[N:15]O)[NH2:14]>N1C=CC=CC=1>[Br:9][C:10]1[CH:11]=[C:12]([C:13]2[N:15]=[C:2]([C:3]([O:5][CH2:6][CH3:7])=[O:4])[O:8][N:14]=2)[CH:17]=[C:18]([Br:21])[C:19]=1[OH:20]

Participants

4

Reactant 2

HCID 20884Ethoxalyl chlorideHCID 46396913,5-Dibromo-N',4-dihydroxybenzimidamide

Product 1

HCID 136139598Ethyl 3-(3,5-dibromo-4-hydroxyphenyl)-1,2,4-oxadiazole-5-carboxylateYield 46%

Reagents, catalysts & solvents 1

HCID 1049PyridineSolvent

Procedure

Ethyl 2-chloro-2-oxoacetate (12.3 g, 82 mmol) was added dropwise to a stirred solution of 3,5-dibromo-N′,4-dihydroxybenzimidamide (25.5 g, 82 mmol) in pyridine (120 mL) and the mixture was stirred at room temperature for 1 hour and then at 60° C. for 2 hours. The resulting suspension was poured onto water (1.5 L) and extracted with ethyl acetate (2×400 mL). The combined extracts were washed with saturated sodium chloride, dried (MgSO4) and evaporated in vacuo to give an oily solid that was purified by flash chromatography to give a colourless powder. Crystallisation from toluene (400 mL) gave the title compound (I 4.7 g, 46%) as colourless crystals. 1H NMR δ (ppm) (DMSO-d6): 1.14 (3H, t), 4.49 (2H, q), 8.14 (2H, s), 10.93 (1H, br s).

Workup

  1. waitat 60° C. for 2 hours
  2. additionThe resulting suspension was poured onto water (1.5 L)
  3. extractionextracted with ethyl acetate (2×400 mL)
  4. washThe combined extracts were washed with saturated sodium chloride
  5. dry with materialdried (MgSO4)
  6. customevaporated in vacuo
  7. customto give an oily solid
  8. customthat was purified by flash chromatography
  9. customto give a colourless powder
  10. customCrystallisation from toluene (400 mL)

Sources & evidence

ORD record
ord-9702d39f347646e5a11fe6a7aafb4c87
Source dataset
uspto-grants-2012_06
Patent number
US08207205B2

Reaction notes

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