Iron‐Catalyzed Three‐Component Cyanoalkylsulfonylation of 2,3‐Allenoic Acids, Sulfur Dioxide, and Cycloketone Oxime Esters: Access to Cyanoalkylsulfonylated Butenolides

An iron‐catalyzed three‐component cyanoalkylsulfonylation of 2,3‐allenoic acids, K2S2O5, and the ring‐opening of cyclobutanone oxime esters is described. The radical tandem cyclization route allows access to diverse cyanoalkylsulfonylated butenolides in moderate to good yields under mild conditions. Moreover, the products are further converted, offering the corresponding derivatives.