Acetic Acid → methyl 1,4-dimethyl-1H-benzimidazole-5-carboxylate

A mixture of methyl 2-methyl-4-(methylamino)-3-nitrobenzoate (90 mg, 0.4 mmol), 10% palladium on charcoal (Degussa type, 90 mg), acetic acid (124 uL, 1.5 mmol), and ethyl acetate (20 mL) was shaken in a Parr hydrogenation apparatus at 40 psi for 18 hours. The reaction mixture was then filtered and concentrated. The residue was dissolved in formic acid was stirred at 100° C. for 1.5 hour. The reaction mixture was concentrated, quenched with ice-water (15 mL) and the pH was adjusted to basic by portion-wise sodium bicarbonate addition then extracted with ethyl acetate. The combined extract was washed with water (2×30 mL), brine (30 mL), dried over sodium sulfate, filtered and concentrated to give methyl 1,4-dimethyl-1H-benzimidazole-5-carboxylate (78 mg, 95% yield). MS (EI) for C 1H12N2O2: 205 (MH+).

1. filtrationThe reaction mixture was then filtered
2. concentrationconcentrated
3. dissolutionThe residue was dissolved in formic acid
4. stirringwas stirred at 100° C. for 1.5 hour
5. concentrationThe reaction mixture was concentrated
6. customquenched with ice-water (15 mL)
7. additionbasic by portion-wise sodium bicarbonate addition
8. extractionthen extracted with ethyl acetate
9. extractionThe combined extract
10. washwas washed with water (2×30 mL), brine (30 mL)
11. dry with materialdried over sodium sulfate
12. filtrationfiltered
13. concentrationconcentrated

ORD record

ord-17a803b72fd4488997610bf16975d36b

Source dataset

uspto-grants-2011_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08012956B2