Cyanogen Bromide → 4,5-Dichloro-2-(3,4-dichlorophenyl)pyrrole-1,3-dicarbonitrile

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Reaction Steps

Potassium t-butoxide (617 mg, 55 mmol) is added in portions to a solution of 3-cyano-4,5-dichloro 2-(3,4-dichlorophenyl)pyrrole (1.52 g, 5 mmol) in anhydrous THF (20 mL). After 30 minutes, a solution of cyanogen bromide (583 mg, 5.5 mmol) in THF (1 mL) is added. The reaction mixture is stored at room temperature overnight. The solvent is removed in a rotary evaporator. The residue is treated with water and extracted with ethyl acetate. The organic layer is washed with water and saturated sodium chloride and dried (MgSO4). Evaporation and crystallization of the residue from ethyl acetate gives while crystals (1.07 g); mp 250.5°-252.0° C.; IR (nujol) 2255, 2245 cm-1 (CN); 13C NMR (DMSO-d6) 102.7 (N--CN), 113.7 (3-CN); Mass spectrum 331.9 (M+1).

Provenance & Evidence