Ferrocene Catalyzed Radical Cascade Cyclization of Aryl 1,6-Diynes: Access to Cyanoalkylsulfonyl Fluorenes

A ferrocene-catalyzed cyanoalkylsulfonylative radical cascade cyclization of aryl 1,6-diynes using cycloketone oxime esters and DABCO.(SO2)(2) (DABSO) is reported. The reaction proceeds with notable chemo- and regioselectivity, without requiring additional oxidants or reductants. Interestingly, the methodology facilitates the formation of an unprecedented dicyanoalkylsulfonylated derivative in the case of electronically deficient aryl 1,6-diynes. Additionally, this transformation is compatible with substrates derived from drugs and bioactive molecules, highlighting its synthetic utility.