Rapid Screening of New Polymer‐Supported Palladium ( II ) Bis(3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes)

Summary: The synthesis of two 1,3‐diaryl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene‐based N ‐heterocyclic carbene‐ (NHC) derived palladium complexes, Pd(5‐hydroxy‐1,3‐bis‐(2,4,6‐trimethylphenyl)‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene)   2 2+(Ag 2 Br 2 Cl 4 )   1/2 4−( 10 ) and Pd(5‐(bicyclo[2.2.1]hept‐5‐ene‐2‐carbonyloxy)‐1,3‐bis‐(2,4,6‐trimethylphenyl)‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene)   2 2+(Ag 2 Br 2 Cl 4 )   1/2 4−( 11 ) is described. 10 was supported on a PS‐DVB and a Wang resin, respectively, to yield catalysts 12 and 13 , while 11 was used for the synthesis of a ring‐opening metathesis precipitation polymerization‐derived support 14 . All supports were tested for their activity in Heck‐type reactions using a combinatorial approach.Structure of polymer supported Pd‐catalysts.