Methanol → methyl 1-ethyl-2-methylbenzimidazole-5-carboxylate
Reaction equation
[CH2:1]([N:3]1[C:7]2[CH:8]=[CH:9][C:10]([C:12]([OH:14])=[O:13])=[CH:11][C:6]=2[N:5]=[C:4]1[CH3:15])[CH3:2].S(Cl)(Cl)=O.[CH3:20]O>>[CH3:20][O:13][C:12]([C:10]1[CH:9]=[CH:8][C:7]2[N:3]([CH2:1][CH3:2])[C:4]([CH3:15])=[N:5][C:6]=2[CH:11]=1)=[O:14]Participants
Procedure
To a suspension of 1.1 g (5.4 mmol) of the title C compound, 1-ethyl-2-methyl-1H-benzoimidazole-5-carboxylic acid in 25 mL of MeOH is added dropwise 0.7 g (5.9 mmol) of thionyl chloride and the resulting solution is stirred at 700 for 6 h, then at RT for 18 h. The solvent is removed under reduced pressure and 8% aqueous NaHCO3 solution is added to the residue. The mixture is extracted with EtOAc and the organic phase is dried over anhydrous Na2SO4. The organic solution is concentrated until the product precipitated. The solid is collected by filtration, washed with EtOH and MTBE to give 1-ethyl-2-methyl-1H-benzoimidazole-5-carboxylic acid methyl ester as a beige solid: mp=118-121° C.; IR (KBr) 3430, 1695 cm−1; 1H-NMR (CDCl3) δ 8.39 (s, 1H), 7.98 (dd, 1H), 7.32 (d, J=8.45, 1H), 4.19 (q, 2H), 3.94 (s, 3H), 2.64 (s, 3H), 1.43 (t, 3H); [M+1]+=219.
Workup
- waitat RT for 18 h
- customThe solvent is removed under reduced pressure and 8% aqueous NaHCO3 solution
- additionis added to the residue
- extractionThe mixture is extracted with EtOAc
- dry with materialthe organic phase is dried over anhydrous Na2SO4
- concentrationThe organic solution is concentrated until the product
- customprecipitated
- filtrationThe solid is collected by filtration
- washwashed with EtOH and MTBE
Sources & evidence
- ORD record
- ord-dffb13e1c45c44af8358731cbebfd3e8
- Source dataset
- uspto-grants-2007_11
- Patent number
- US07291635B2
Reaction notes
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