Two L-proline-based linear polystyrene anchored catalysts (1a-b) have been efficiently synthesized. By using only 5 mol% of catalysts, the corresponding products of the aldol reaction were obtained in good yields (up to 91%) with excellent anti diastereoselectivity (up to 93:7) and enantioselectivity (up to 98% ee) in DMF in the presence of water. The yields of these reactions in the ketone/water mixture were lower than those in wet DMF (up to 84%). However, the stereoselectivity was comparable (up to 92:8 anti/syn ratio and 96% ee, respectively). In addition, catalysts 1a-b could be recovered by a simple precipitation and filtration process. They can also be re-used for at least five times without obvious loss of catalytic efficiency.
Some efficient polymer-supported palladium catalysts have been synthesized. Their catalytic effects were evaluated in the Heck reaction of iodobenzene with acrylates or styrene. High catalytic activities were achieved with turn over frequencies (TOF) up to 28000 and 6250, respectively. For the reaction of iodobenzene with styrene, high stereoselectivity was obtained. Additionally, the catalysts could be recovered by a simple filtration progress and can be reused for at least 5 times with a slow progressive decrease in activity.
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