Lithium Bromide → 9-Benzyl-9H-carbazol-4-ol

HRID 1057593Notes

Reaction equation

HRID 1057593 reaction equation
[CH2:1]([N:8]1[C:20]2[CH2:19][CH2:18][CH2:17][C:16](=[O:21])[C:15]=2[C:14]2[C:9]1=[CH:10][CH:11]=[CH:12][CH:13]=2)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.Br.[NH+]1C=CC=CC=1.CCOC(C)=O.CCCCCC.[Li+].[Br-]>C1COCC1.CN(C=O)C>[CH2:1]([N:8]1[C:20]2[CH:19]=[CH:18][CH:17]=[C:16]([OH:21])[C:15]=2[C:14]2[C:9]1=[CH:10][CH:11]=[CH:12][CH:13]=2)[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1

Participants

7

Reactant 4

HCID 82050Lithium BromideHCID 27279169-Benzyl-1,2,3,9-tetrahydro-4H-carbazol-4-oneHCID 21226041Pyridinium hydrobromideHCID 21226206Ethyl acetate hexane

Product 1

HCID 113693279-Benzyl-9H-carbazol-4-olYield 72%

Reagents, catalysts & solvents 2

HCID 6228DimethylformamideSolvent3×HCID 8028TetrahydrofuranSolvent2×

Procedure

To a mixture of 9-Benzyl-1,2,3,9-tetrahydro-4H-carbazol-4-one (3.89 g, 14.13 mmol), THF (20 mL) in THF (20 mL) and DMF (15 mL) is added pyridinium hydrobromide perbromide (5.42 g, 16.96 mmol) as a solution in DMF (5 mL). After stirring for 5 h at room temperature, TLC (EtOAc-hexane, 20/80) showed little or no reaction had occurred, so the mixture is stirred at 70° C. for 4 h and then allowed to cool (and stir the remainder of the night). The solvents then are removed and the residue is partitioned between Et2O and brine, dil. Na2S2O3, and brine. The aqueous layer is removed and CH2Cl2 is added to the organic layer (from which solids had begun to precipitate). The organic layers are dried over MgSO4 and taken to dryness. Without further purification, the crude product is stirred with LiBr (2.67 g, 31 mmol) and Li2CO3 (2.07 g, 28 mmol) in DMF (50 mL) at 100° C. for 45 min, and then at reflux for 3 h. After cooling, the solvent is removed and the residue is partitioned between CH2Cl2 and water. The organic layers are dried over sodium sulfate and concentrated to dryness. The residue is chromatographed on silica gel (250 mL) using EtOAc-heptane (15/85)/CH2Cl2 (6:1) as eluent to give 2.78 g of solid; mp 119-121.5° C.; IR (drift) 3353, 1602, 1485, 1458, 1337, 1328, 1279, 1230, 1138, 1104, 780, 748, 735, 714, 700 cm−1; 1H NMR (CDCl3) δ5.32, 5.50, 6.60, 6.97, 7.14, 7.26, 7.3-7.4, 8.33. Anal. Calcd for C19H15NO: C, 83.49; H, 5.53; N, 5.12. Found: C, 82.35; H, 5.51; N, 5.06.

Workup

  1. stirringis stirred at 70° C. for 4 h
  2. temperatureto cool (and
  3. stirringstir the remainder of the night)
  4. customThe solvents then are removed
  5. customthe residue is partitioned between Et2O and brine, dil. Na2S2O3, and brine
  6. customThe aqueous layer is removed
  7. additionCH2Cl2 is added to the organic layer (from which solids had begun to precipitate)
  8. dry with materialThe organic layers are dried over MgSO4
  9. customWithout further purification
  10. temperatureat reflux for 3 h
  11. temperatureAfter cooling
  12. customthe solvent is removed
  13. customthe residue is partitioned between CH2Cl2 and water
  14. dry with materialThe organic layers are dried over sodium sulfate
  15. concentrationconcentrated to dryness
  16. customThe residue is chromatographed on silica gel (250 mL)

Sources & evidence

ORD record
ord-ef8432ffa0664158811ee1a7eb6edf4c
Source dataset
uspto-grants-2003_02
Patent number
US06514968B1

Reaction notes

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