Pd/Al（OH）₃ Nanoparticles-Catalyzed Heck Cross-Coupling Reactions Of Aryl Halides

As a most effective method in carbon-carbon bond formation, The Mizoroki-Heck cross-coupling reaction is being extensive used in modern organic synthesis and plays an extremely important role in the synthesis of many drugs and natural products. Therefore, extensive attentions have been focused on this reactions for a long time. In this paper, we used nano-palladium catalyst to further study the Heck coupling reactions of aryl halides with olefins.The reaction conditions were optimized which had been focused on the base, base dose, solvent, solvent dose, Pd loading, material ratio and so on. The products were examined by TLC,1HNMR. The optimal reaction conditions: iodobenzene 0.2 mmol as standard substrate, olefin 1.2 equiv, nano-palladium 0.1 mol% as the catalyst, K3PO41.5 equiv as base, DMF 0.8 mL as solvent at 60℃ which provided ideal product 98% isolated yield. Next, a variety of aryl halides were examined for the cross-coupling reactions using optimized conditions. The results showed that aryl iodides bearing electron-withdrawing and electron-donating gave products in good to excellent yields. Subsequently, the reactions of aryl bromides with butyl acrylate were examined using TBAB for solvent. The results showed that the reaction of aryl bromides mostly generated coupled products in moderate to good yields. At last, the reactions of aryl chlorides with butyl acrylate and aryl bromides with aryl olefins were carried out in TBAB/DMF. The results showed that somewhat sluggish yields were obtained when aryl chlorides were used as the substrates. However, the reaction of aryl bromides with aryl olefins bearing electron-withdrawing and electron-donating gave products in good to excellent yields.The advantages of this method included:(1) easily available, high activity; (2) mild reaction conditions, high product yield; (3) be stable to air and water, easy operation.