Dimethylformamide → 6,7-Dichloro-2-formyl-5-hydroxybenzo[b]thiophene

HRID 1903483Notes

Reaction equation

HRID 1903483 reaction equation
[Cl:1][C:2]1[C:3]([OH:12])=[CH:4][C:5]2[CH:9]=[CH:8][S:7][C:6]=2[C:10]=1[Cl:11].C([Li])CCC.CN(C)[CH:20]=[O:21]>O1CCCC1>[Cl:1][C:2]1[C:3]([OH:12])=[CH:4][C:5]2[CH:9]=[C:8]([CH:20]=[O:21])[S:7][C:6]=2[C:10]=1[Cl:11]

Participants

5

Reactant 3

HCID 6228DimethylformamideHCID 132899976,7-Dichloro-1-benzothiophene-5-olHCID 178418339Butyllithium

Product 1

HCID 132900376,7-Dichloro-2-formyl-5-hydroxybenzo[b]thiophene

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A solution of 8.7 g of 6,7-dichloro-5-hydroxybenzo[b]thiophene in 50 ml of anhydrous tetrahydrofuran is placed in a 250 ml 3-necked flask and cooled to -25°. To the solution under nitrogen, is added dropwise 42 ml of a solution of 2.5 M n-butyllithium at a rate such that the temperature did not rise above -10°. After total addition, the mixture is stirred at 0°-5° for 3 hrs. To the mixture is added 14 ml of anhydrous dimethylformamide over a period of 20 mins. The reaction mixture is allowed to warm to room temperature and stirred for 1 hr. Quenching with 400 ml of 2 N hydrochloric acid, followed by extraction with ethyl acetate, gives a precipitate. Recrystallization from acetone-hexane affords 6.5 g of 6,7-dichloro-2-formyl-5-hydroxy-benzo[b]thiophene, mp 197°-198°.

Workup

  1. temperaturecooled to -25°
  2. customdid not rise above -10°
  3. additionAfter total addition
  4. stirringstirred for 1 hr
  5. customQuenching with 400 ml of 2 N hydrochloric acid
  6. extractionfollowed by extraction with ethyl acetate
  7. customgives a precipitate
  8. customRecrystallization from acetone-hexane

Sources & evidence

ORD record
ord-13f88f27a29a4f2eb3d5940e471d6256
Source dataset
uspto-grants-1984_03
Patent number
US04436748

Reaction notes

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