Selected Examples for Dendritic Polymer-supported Catalysis

1 Selected Examples for Dendritic Polymer-supported Catalysis (see Tab. 7.2) 

An instructive example for a positive dendritic effect was reported by Reetz et al. [71]. The authors described a poly(propylenimine) dendrimer, with diphenylphos-phine groups in the periphery (Fig. 7.20). A dendritic [PdMe2]-complex was tested as an efficient catalyst in the Heck reaction of bromobenzene and styrene to yield stilbene (85-90% conversion). The separation technique originally investigated for 

An extension of these dendritic phosphine ligands for Pd-catalyzed allylic ami-nation was recently described using a thermomorphic system for separation [72]. 

In this case an active dendritic Pd°-species could be generated by hydrazine reduction and subsequently used in a DMF/heptane mixture at 75 °C for the stereoselective allylic amination. After completion of the reaction and cooling to room temperature, the catalysts can be recovered by simple phase separation. 

The use of soluble dendrimers with phospine ligands experienced a rapid growth and was also transferred to several other dendrimer scaffolds [64—66]. Many reactions, such as hydrogenation, hydrovinylation, Stille coupling, Knoeve-nagel condensation and Michael addition were reported (Tab. 7.2) [73, 74]. 

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