Benzene → 8-Bromo-3-(di-n-propylamino)-5-methoxychroman

HRID 1464695Notes

Reaction equation

HRID 1464695 reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][C:5]([O:13][CH3:14])=[C:6]2[C:11]=1[O:10][CH2:9][C:8](=O)[CH2:7]2.O.[C:16]1([CH3:26])[CH:21]=CC(S(O)(=O)=O)=CC=1.[C:27]([BH3-])#[N:28].[Na+].[OH-].[Na+].Cl.[CH:34]1C=CC=C[CH:35]=1>CO.O>[Br:1][C:2]1[CH:3]=[CH:4][C:5]([O:13][CH3:14])=[C:6]2[C:11]=1[O:10][CH2:9][CH:8]([N:28]([CH2:21][CH2:16][CH3:26])[CH2:27][CH2:34][CH3:35])[CH2:7]2

Participants

9

Reactant 6

HCID 241BenzeneHCID 313Hydrochloric Acid2×HCID 14798Sodium HydroxideHCID 521998p-Toluenesulfonic acid monohydrateHCID 5003444Sodium cyanoborohydrideHCID 147034268-Bromo-5-methoxy-3-chromanone

Product 1

HCID 147034278-Bromo-3-(di-n-propylamino)-5-methoxychroman

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 962WaterSolvent

Procedure

To a solution of 8-bromo-5-methoxy-3-chromanone (550 mg, 2.14 mmol) in benzene (40 ml), di-n-propylamino (1.8 ml, 13.2 mmol) and p-toluenesulfonic acid, monohydrate (41 mg, 0.32 mmol) was added. The solution was refluxed for 5 hours with a Dean-Stark apparatus under nitrogen atmosphere. After cooling to room temperature a solution of sodium cyanoborohydride (2.0 g, 32 mmol) dissolved in MeOH (50 ml) was added and thereafter stirred overnight. Water was added (50 ml) and 5% NaOH-solution (5ml). The solution was extracted with CH2Cl2. The organic layer was separated, washed with water and dried (Na2SO4). The solvent was evaporated and the residue was chromatographed (SiO2) with light petroleum-ether (3:1) as eluant yielding 550 mg (75%) as an oil. The amine was converted to its hydrochloride with HCl-saturated ethanol. Evaporation and recrysstallization (ethanol-ether) gave the product as crystals.

Workup

  1. temperatureThe solution was refluxed for 5 hours with a Dean-Stark apparatus under nitrogen atmosphere
  2. additionwas added
  3. extractionThe solution was extracted with CH2Cl2
  4. customThe organic layer was separated
  5. washwashed with water
  6. dry with materialdried (Na2SO4)
  7. customThe solvent was evaporated
  8. customthe residue was chromatographed (SiO2) with light petroleum-ether (3:1) as eluant
  9. customyielding 550 mg (75%) as an oil
  10. customEvaporation and recrysstallization (ethanol-ether)

Sources & evidence

ORD record
ord-8f018217d19e4d9eb8caf1f76ddb1ad2
Source dataset
uspto-grants-1994_04
Patent number
US05306830

Reaction notes

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