AbstractC(sp3)−C(sp2) cross‐coupling reactions are an indispensable tool for organic synthesis. In these reactions transition metals have been extensively employed to promote the formation of valuable carbon‐carbon bonds. Herein, we report our recent discovery of a designer thioether as a highly active organocatalyst for reactions between an allyl bromide and an arylboronic acid. The cross‐coupling event occurred readily under mild condition in the presence of a weak inorganic base. Preliminary mechanistic studies suggested a sulfonium ylide mechanism.