2-Thiophenecarboxaldehyde → Benzoxazole, 5-nitro-2-(2-thienyl)-

HRID 1287661Notes

Reaction equation

HRID 1287661 reaction equation
[N+:1]([C:4]1[CH:9]=[CH:8][C:7]([OH:10])=[C:6]([NH2:11])[CH:5]=1)([O-:3])=[O:2].[S:12]1[CH:16]=[CH:15][CH:14]=[C:13]1[CH:17]=O.C([O-])(=O)C.C([O-])(=O)C.C([O-])(=O)C.C([O-])(=O)C.[Pb+4]>C(O)(=O)C.O>[N+:1]([C:4]1[CH:9]=[CH:8][C:7]2[O:10][C:17]([C:13]3[S:12][CH:16]=[CH:15][CH:14]=3)=[N:11][C:6]=2[CH:5]=1)([O-:3])=[O:2]

Participants

6

Reactant 3

HCID 73642-ThiophenecarboxaldehydeHCID 36133892-Amino-4-NitrophenolHCID 178418268HCID 178418268, compound

Product 1

HCID 11253621Benzoxazole, 5-nitro-2-(2-thienyl)-Yield 50.4%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolvent2×HCID 962WaterSolvent

Procedure

Step A - 15.4 g of 4-nitro-o-aminophenol and 11.2 g of thiophenecarboxaldehyde are dissolved in glacial acetic acid (450 ml) and heated to 85°. 44.4 g of lead tetraacetate is dissolved in 400 ml glacial acetic acid by warming and added to the above solution. Heating is continued for 0.5 hr and the solution is cooled to room temperature, diluted with an equal volume of water and the dark precipitate is collected and washed with additional water. The crude product is dissolved in CH2Cl2 (800 ml) and heated with 2.0 g of "Darco" G-60, followed by evaporation of the CH2Cl2. The resulting material is recrystallized from ethanol-chloroform (3:1) to yield 12.4 g of 5-nitro-2-(2-thienyl)benzoxazol, mp 186°-188°.

Workup

  1. temperatureheated to 85°
  2. temperatureby warming
  3. additionadded to the above solution
  4. temperatureHeating
  5. customthe dark precipitate is collected
  6. washwashed with additional water
  7. dissolutionThe crude product is dissolved in CH2Cl2 (800 ml)
  8. temperatureheated with 2.0 g of "Darco" G-60,
  9. customfollowed by evaporation of the CH2Cl2
  10. customThe resulting material is recrystallized from ethanol-chloroform (3:1)

Sources & evidence

ORD record
ord-46403719ce504437aa8c86c2d4845b6e
Source dataset
uspto-grants-1976_10
Patent number
US03985755

Reaction notes

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