Hydrochloric Acid → 6-Methoxythianaphthen-2-one

HRID 1706Notes

Reaction equation

HRID 1706 reaction equation
CN(C)[C:3]1[S:7][C:6]2[CH:8]=[C:9]([O:12][CH3:13])[CH:10]=[CH:11][C:5]=2[CH:4]=1.Cl.[O:16]1CCCC1>>[CH3:13][O:12][C:9]1[CH:10]=[CH:11][C:5]2[CH2:4][C:3]([S:7][C:6]=2[CH:8]=1)=[O:16]

Participants

4

Reactant 3

HCID 313Hydrochloric AcidHCID 8028TetrahydrofuranHCID 10512530Benzo[b]thiophen-2-amine, 6-methoxy-N,N-dimethyl-

Product 1

HCID 154582606-Methoxythianaphthen-2-oneYield 80%

Procedure

To tetrahydrofuran (200 mL) containing 2-dimethylamino-6-methoxybenzo-[b]-thiophene (cf. U.S. Pat. No. 5,420,349) (20.00 g, 96.5 mmol) was added 1N aqueous HCl (200 mL) and the resulting mixture was heated to reflux for 3 h. The mixture was cooled, the layers were separated, and the aqueous layer was extracted with dichloromethane (300 mL). The combined organic layers washed with water (250 mL), dried (MgSO4), filtered and concentrated to give crude product, which was recrystallized from 3A-ethanol, and dried in vacuo at room temperature to afford the title compound (13.89 g, 77.0 mmol, 80%): mp 80°-82° C.; IR (KBr) 1713, 1605, 1485, 1287, 1015, 865, 813 cm-1 ; 1H NMR (DMSO-d6) δ7.22 (d, 1H, J=8.4 Hz), 7.11 (s, 1H), 6.78 (d, 1H, J=8.4 Hz), 4.06 (s, 2H), 3.71 (s, 3H); 13 C NMR (DMSO-d6) δ203.5, 159.0, 136.9, 125.6, 124.6, 112.3, 108.4, 55.3, 46.2. Anal. Calcd. for C9H8O2S: C, 59.98; H, 4.47; S, 17.78. Found: C, 60.19; H, 4.57; S, 18.03.

Workup

  1. temperaturethe resulting mixture was heated
  2. temperatureto reflux for 3 h
  3. temperatureThe mixture was cooled
  4. customthe layers were separated
  5. extractionthe aqueous layer was extracted with dichloromethane (300 mL)
  6. washThe combined organic layers washed with water (250 mL)
  7. dry with materialdried (MgSO4)
  8. filtrationfiltered
  9. concentrationconcentrated
  10. customto give crude product, which
  11. customwas recrystallized from 3A-ethanol
  12. customdried in vacuo at room temperature

Sources & evidence

ORD record
ord-71828877dd4a46a7a0bca4e4e2ebc272
Source dataset
uspto-grants-1998_03
Patent number
US05726186

Reaction notes

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