Methanol → Methyl 6-hydroxy-3-methylbenzo[b]thiophene-2-carboxylate

HRID 1583359Notes

Reaction equation

HRID 1583359 reaction equation
B(Br)(Br)Br.[CH3:5][O:6][C:7]([C:9]1[S:13][C:12]2[CH:14]=[C:15]([O:18]C)[CH:16]=[CH:17][C:11]=2[C:10]=1[CH3:20])=[O:8].CO>C(Cl)Cl>[CH3:5][O:6][C:7]([C:9]1[S:13][C:12]2[CH:14]=[C:15]([OH:18])[CH:16]=[CH:17][C:11]=2[C:10]=1[CH3:20])=[O:8]

Participants

5

Reactant 3

HCID 887MethanolHCID 25134Boron tribromideHCID 13662973HCID 13662973, compound

Product 1

HCID 13662997Methyl 6-hydroxy-3-methylbenzo[b]thiophene-2-carboxylateYield 81%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

Boron tribromide (5.0 ml.) was added dropwise to a stirred solution of 6-methoxy-3-methylbenzo[b]thiophene-2-carboxylic acid methyl ester (4.70 g.) in dry methylene chloride (200 ml.) at -78° C. and the resulting suspension was stirred at -78° for 15 minutes followed by 24 hours at room temperature. The mixture was then treated cautiously with methanol and the solution was washed with sodium bicarbonate solution. The organic layer was dried (Na2SO4) and evaporated to give a solid which was chromatographed on silica gel. Elution with chloroform first gave a trace of impurity followed by pure product. The product-containing fractions were evaporated to give a solid which was crystallized from ethyl acetate/petrol (b.p. 60°-80°) to give 6-hydroxy-3-methylbenzo[b]thiophene-2-carboxylic acid methyl ester (3.58 g.), m.p. 174°-176°.

Workup

  1. waitfollowed by 24 hours at room temperature
  2. washthe solution was washed with sodium bicarbonate solution
  3. dry with materialThe organic layer was dried (Na2SO4)
  4. customevaporated
  5. customto give a solid which
  6. customwas chromatographed on silica gel
  7. washElution with chloroform
  8. customfirst gave a trace of impurity
  9. customThe product-containing fractions were evaporated
  10. customto give a solid which
  11. customwas crystallized from ethyl acetate/petrol (b.p. 60°-80°)

Sources & evidence

ORD record
ord-0f0249ad0bcd4687af30b329d6fc4235
Source dataset
uspto-grants-1985_11
Patent number
US04551468

Reaction notes

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