Acetanilide → 2-methyl-1-phenyl-1H-benzimidazole

Participants

Reaction Conditions

Reaction Steps

A reaction tube containing 2-iodonitrobenzene (125 mg, 0.5 mmol), N-phenylacetamide (81 mg, 0.6 mmol), CuI (4.8 mg, 0.025 mmol), N-methylethylenediamine (4.4 μL, 0.05 mmol), potassium phosphate (212 mg, 1 mmol) in dry toluene (3 mL) was purged with dry argon for 3 min. Then the mixture was heated at 100° C. for 18 h. After cooling, the reaction was hydrolyzed with 3 mL of water and filtered through a Varian cartridge Chem Elut 12198007, rinsing with ethyl acetate. The crude mixture was dissolved in 10 mL of glacial acetic acid and refluxed for 30 min in the presence of iron powder (279 mg, 5 mmol). The acid was removed under reduced pressure and the residue was suspended in saturated sodium bicarbonate solution and extracted with ethyl acetate. The obtained crude was purified by preparative HPLC, affording the title compound as a yellow solid (82 mg, 78% yield). mp 46-48° C. 1H NMR δ 2.63 (m, 3 H), 7.32 (d, J=Hz, 1 H), 7.47 (t, J=Hz, 1 H), 7.53 (t, J=Hz, 1 H), 7.66-7.72 (m, 5 H), 7.88 (d, J=7.2 Hz, 2 H); 13C NMR δ 12.6, 111.8, 115.1, 125.3, 127.1, 130.2, 130.3, 132.9, 133.8, 152.2, 158.3. HRMS (FAB): cal. for C14H13N2 [M+H+]: 209.1079; found: 209.1072. The same reaction was also performed on 25 mmol scale, obtaining the final product in 75% yield (3.9 g). The same product was obtained from 2-bromonitrobenzene (101 mg, 0.5 mmol) in 80% yield (83 mg).

Provenance & Evidence