Phosphorus oxychloride → 2-Chloro-5-iodo-1H-benzo[d]imidazole

Participants

Reaction Conditions

Reaction Steps

5-Iodo-1,3-dihydro-2H-1,3-benzimidazole-2-one (7 g) [see Preparation 24] was added to a solution of phosphoryl chloride (135 ml). The reaction mixture was then heated to 120° C. and stirred for 2 hours, after which time the phosphoryl chloride was removed under reduced pressure and the residue diluted with water. The residual aqueous solution was neutralised with aqueous potassium hydrogen carbonate solution and the product extracted with 90:10, by volume, dichloromethane:methanol, dried over magnesium sulphate and the solvent removed under reduced pressure to afford 2-chloro-6-iodo-1H-1,3-benzimidazole (3.68 g) as a white solid.

Provenance & Evidence