Metal‐catalyzed Cyanoalkylsulfonylation/Cyanoalkylation of N‐propenyl‐2‐Benzimidazole: Access to Cyanoalkylsulfonyl/Cyanoalkylbenzimidazole[2,1‐a] Iso‐Quinoline‐6(5H)‐Ones

Abstract The three‐component cyanoalkylsulfonylation cyclization reaction of N ‐methacryloyl‐2‐phenylbenzimidazole, DABCO ⋅ (SO 2 ) 2 and cyclobutanone oxime ester regulated by different metals (iron and nickel) and the two‐component cyanoalkylation cyclization reaction of DABCO ⋅ (SO 2 ) 2 as oxidant were described. The tandem cyclization route allows different cyanoalkylsulfonylated benzimidazole [2,1‐a] iso‐quinoline‐6(5H)‐ones/cyanoalkylated benzimidazole [2,1‐a] iso‐quinoline‐6(5H)‐ones to be obtained in moderate to good yields under mild conditions, with good functional group tolerance, readily available starting materials, and simple operation. In addition, experiments show that the tandem cyclization reaction was a free radical reaction process.