Forcing a cis‐Product by Matrix Imprinting: Heck Reaction Catalyzed by Palladium Acetate Entrapped within cis‐Imprinted Sol‐Gel Derived Silicates

While the Heck coupling of aryl bromides with styrenes by palladium acetate entrapped within octylated silica sol‐gel forms almost entirely trans‐stilbenes, the catalysis by the palladium compound within the cis‐pre‐imprinted support gives stilbenes that are substantially enriched by cis‐oriented isomers. Although the ceramic support is completely freed from the imprint prior to the coupling process, cis‐stilbenes are formed with similar selectivities upon recycling of the catalyst systems for at least four consecutive runs.