Methanol → 2-(4-Chlorophenyl)-3H-imidazo[4,5-b]pyridine-3-acetic acid methyl ester
Reaction equation
[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[N:16]([CH2:17][C:18]([OH:20])=[O:19])[C:11]3=[N:12][CH:13]=[CH:14][CH:15]=[C:10]3[N:9]=2)=[CH:4][CH:3]=1.S(=O)(=O)(O)O.[CH3:26]O>>[CH3:26][O:19][C:18](=[O:20])[CH2:17][N:16]1[C:11]2=[N:12][CH:13]=[CH:14][CH:15]=[C:10]2[N:9]=[C:8]1[C:5]1[CH:6]=[CH:7][C:2]([Cl:1])=[CH:3][CH:4]=1Participants
Procedure
A solution of 2-(4-chlorophenyl)-3H-imidazo[4,5-b]pyridine-3-acetic acid (3.1 g, 0.1011 mole), methanol (100 ml) and concentrated sulfuric acid (3 ml) was refluxed overnight under a Dean-Stark trap. Another 2 ml of concentrated sulfuric acid and methanol (50 ml) was added and reflux continued for 12 hr. The methanol was evaporated, water (50 ml) was added, and sodium bicarbonate (solid) added until basic. The mixture was extracted with ethyl acetate (3×25 ml). The combined ethyl acetate extracts were washed with water (25 ml), dried over sodium sulfate, and concentrated in vacuo. The residue (2.5 g) was combined with a sample obtained previously and recrystallized from isopropyl ether-isopropyl alcohol to give 3.0 g (56%) of white needles, mp 198°-200° C.
Workup
- temperaturereflux
- customThe methanol was evaporated
- additionwater (50 ml) was added
- additionsodium bicarbonate (solid) added until basic
- extractionThe mixture was extracted with ethyl acetate (3×25 ml)
- washThe combined ethyl acetate extracts were washed with water (25 ml)
- dry with materialdried over sodium sulfate
- concentrationconcentrated in vacuo
- customobtained previously
- customrecrystallized from isopropyl ether-isopropyl alcohol
Sources & evidence
- ORD record
- ord-1a2df4fa902f4d1a9a9739d33f11cc5d
- Source dataset
- uspto-grants-1990_08
- Patent number
- US04948800
Reaction notes
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