2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → 2-(3,4,5-trimethoxyphenyl)-1H-benzimidazole

Participants

Reaction Steps

To a solution of 1,2-phenylenediamine (30 mmole, 3.24 g) and 3,4,5-trimethoxybenzaldehyde (30 mmole, 5.89 g) in acetonitrile (75 ml) is added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (30 mmole, 6.81 g), and the mixture is stirred 18 hours at room temperature. Sodium hydroxide (0.5M, 120 ml) is added, and the mixture is stirred over night at room temperature. The dark precipitate is filtered off and is digested with ethanol (30 ml) to give the title product as a brown solid (14%). (R1=hydrogen, R2=3,4,5-trimethoxyphenyl, n=0). 1H-NMR (DMSO, TMS, δ): 3.74 (s, 3H, OCH3), 3.91 (s, 6H, OCH3), 7.20 (m, 2H, ar), 7.54 (s, 2H, ar), 7.61 (m, 2H, ar).

Provenance & Evidence