AbstractThe chemical reactivity of citraconimide (3‐methylmaleimide, 2) has been investigated with special emphasis being placed on the use of mild and selective reaction conditions. Particular attention has been focused on the theiotropic reactivity of citraconimide. The results indicate that the reaction of various mercaptans with citraconimide is highly regioselective resulting predominately in the geminally substituted products with the percentage of vicinally substituted products increasing as a function of the steric bulk of the alkyl mercaptan. Additional studies on the double bond of citraconimide have furnished 4‐halogeno‐ and the 3,4‐dihydro derivatives of citraconimide. Several N‐substituted citraconimide derivatives have also been prepared.