Recyclable Polymer-Supported Pd Catalysts for Aryl Amination Reactions

Significance

The authors have prepared polymer-supported palladium catalysts from three commercially available phosphine-functionalized polystyrenes, Pd₂(dba)₃, and P(t-Bu)₃. The stability of the catalysts is dependent on the method of preparation and the nature of the polymer-bound phosphine. Thus, substantial catalyst leaching (determined by VT ³¹P NMR spectroscopy) and/or decomposition (indicated by the deposition of palladium black) were observed for all the catalysts prepared by method A. The catalyst (PS-PCy₂)Pd[P(t-Bu)₃], prepared by method B, was stable even at 100 ºC, though leaching was observed in the case of catalysts prepared from PS-PPh₂ and PS-CH₂PPh₂. (PS-PCy₂)Pd[P(t-Bu)₃] prepared by method B can be reused in the amination of chlorotoluene without loss in yield (first run: >95%, second run: >95%).