反应详情

To a solution of 3-amino-4-methylaminobenzoic acid ethyl ester (388 mg) and 2,6-dichlorobenzaldehyde (350 mg) in DMSO (4 mL) was added Yb(OTf)3 (50 mg) and the solution was stirred at room temperature for 24 h. More Yb(OTf)3 was added and stirring was continued for 24 h. This process was repeated another two times. The reaction mixture was partioned between water and EtOAc. The aqueous layer was extracted with EtOAc. The combined organic layers were dried, filtered and concentrated. The residue was purified by flash chromatography using a gradient of ethyl acetate/CH2Cl2 (0% to 25%) to give 2-(2,6-dichlorophenyl)-1-methyl-1H-benzoimidazole-5-carboxylic acid ethyl ester as a beige solid, mp=164-166° C.; MS (m/z) 349 (M+1).

1. stirringstirring
2. waitwas continued for 24 h
3. extractionThe aqueous layer was extracted with EtOAc
4. customThe combined organic layers were dried
5. filtrationfiltered
6. concentrationconcentrated
7. customThe residue was purified by flash chromatography