Propionic Acid → 1H-Pyrrolo[3,2-b]pyridine-3-carbaldehyde
Reaction equation
CN(C)[C:3]1[C:7]2=[N:8][CH:9]=[CH:10][CH:11]=[C:6]2[NH:5][CH:4]=1.C1N2CN3CN(C2)CN1C3.[C:23](O)(=[O:26])CC>>[CH:23]([C:3]1[C:7]2=[N:8][CH:9]=[CH:10][CH:11]=[C:6]2[NH:5][CH:4]=1)=[O:26]Participants
Procedure
A solution of 3-dimethylamino-1H-pyrrolo[3,2-b]pyridine (1.53 g) and hexamethylenetetramine (1.22 g) in 6.68 g of 66% propionic acid was added dropwise to a refluxing solution of 2.44 g of hexamethylenetetramine in 8.92 g of the same solvent. The addition was carried out over a period of one hour and the solution was refluxed 3.5 hours more. The solution was concentrated in vacuo and thereto water (30 ml), ethyl acetate (25 ml), and tetrahydrofuran (20 ml) were added. The organic layer was separated, dried over sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by column chromatography on silica gel (12 g) using a mixed solvent of dichloromethane and methanol (0.15:1). The fractions containing the objective compound were collected and evaporated under reduced pressure to give a powder of 3-formyl-1H-pyrrolo[3,2-b]pyridine (0.45 g).
Workup
- additionThe addition
- temperaturethe solution was refluxed 3.5 hours more
- concentrationThe solution was concentrated in vacuo
- additionwater (30 ml), ethyl acetate (25 ml), and tetrahydrofuran (20 ml) were added
- customThe organic layer was separated
- dry with materialdried over sodium sulfate
- concentrationconcentrated under reduced pressure
- customThe resulting residue was purified by column chromatography on silica gel (12 g)
- additionThe fractions containing the objective compound
- customwere collected
- customevaporated under reduced pressure
Sources & evidence
- ORD record
- ord-2d18397013d144b6b73798c9720a6531
- Source dataset
- uspto-grants-2007_01
- Patent number
- US07166598B2
Reaction notes
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