Sodium Carbonate → Pyrrole-2-carboxaldehyde

HRID 1199399Notes

Reaction equation

HRID 1199399 reaction equation
P(Cl)(Cl)(Cl)=O.[CH2:6]([N:8]([N:15]1[CH:19]=[CH:18][CH:17]=[CH:16]1)[C:9]1C=CN=CC=1)[CH3:7].O.O.O.[C:23]([O-:26])(=[O:25])[CH3:24].[Na+].C(=O)([O-])[O-].[Na+].[Na+]>ClC(Cl)C.O.CN(C)C=O>[NH:15]1[CH:16]=[CH:17][CH:18]=[C:19]1[CH:23]=[O:25].[NH:8]1[CH:6]=[CH:7][C:24]([CH:23]=[O:26])=[CH:9]1

Participants

9

Reactant 4

HCID 10340Sodium CarbonateHCID 24813Phosphorus oxychlorideHCID 10845273N-ethyl-N-(1H-pyrrol-1-yl)-4-pyridinamineHCID 23665404Sodium Acetate Trihydrate

Product 2

HCID 13854Pyrrole-2-carboxaldehydeHCID 6403081H-pyrrole-3-carboxaldehyde

Reagents, catalysts & solvents 3

HCID 962WaterSolventHCID 6228DimethylformamideSolventHCID 63651,1-DichloroethaneSolvent

Procedure

To cold dimethylformamide (11.1 g) was slowly added phosphorous oxychloride (23.2 g). The resultant clear complex was stirred one hour at ambient temperature and thereafter a solution of N-ethyl-N-(1H-pyrrol-1-yl)-4-pyridinamine (20.5 g) in 135 ml of dichloroethane was added. After stirring twelve hours at 95° the reaction mixture was cooled and hydrolyzed for one hour at 95° with a solution of sodium acetate trihydrate (40 g) in 150 ml of water. The reaction mixture was cooled, basified with sodium carbonate and extracted with dichloromethane. The organic extract was washed with water and saturated sodium chloride solution and thereafter dried over anhydrous magnesium sulfate, filtered and evaporated to 24 g of an oil. This oil was purified first by flash chromatography (silica, dichloromethane, then 10% ethyl acetate in dichloromethane), then by high-pressure liquid chromatography (silica, ethyl acetate) to give 8 g of the pyrrol-2-aldehyde as an oil and 8 g of the pyrrol-3-aldehyde as an oil. 2.5 g of the pyrrol-2-aldehyde was converted to the hydrochloride salt in 2-propanol to give 2.2 g of crystals, mp 214°-215° C.

Workup

  1. stirringAfter stirring twelve hours at 95° the reaction mixture
  2. temperatureThe reaction mixture was cooled
  3. extractionextracted with dichloromethane
  4. extractionThe organic extract
  5. washwas washed with water and saturated sodium chloride solution
  6. dry with materialdried over anhydrous magnesium sulfate
  7. filtrationfiltered
  8. customevaporated to 24 g of an oil
  9. customThis oil was purified first by flash chromatography (silica, dichloromethane

Sources & evidence

ORD record
ord-a7d8468e7e884e4094d98c7b9df32497
Source dataset
uspto-grants-1990_02
Patent number
US04900742

Reaction notes

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