Synthesis And Catalytic Performance Of Palladium(?) Complexes Modified With High Sterically Hindered Azole Ligands

The C-C coupling reaction catalyzed by transition metal is one of the most core and common methods for constructing carbon skeleton in the synthesis of natural products and drugs.Among them,the C-C coupling reaction catalyzed by transition metal palladium,especially the Suzuki-Miyaura cross-coupling reaction,has good adaptability.At present,the Suzuki-Miyaura cross-coupling reaction catalyzed by transition metal palladium has become one of the most important and basic methods for synthesizing biaryl derivatives.So,more and more attention has been paid to the design and synthesis of stable and efficient palladium catalysts.The research contents of this paper are as follows:1.A series of NHC-Pd?II?-azole complexes bearing sterically hindered ligands were designed and synthesized.All these complexes were applied in the Suzuki-Miyaura cross-coupling reaction of sterically hindered aryl chlorides.Good to excellent isolated yields of sterically hindered biaryls were obtained with low catalysts loadings?0.1 mol%?,using water and isopropanol?1:1,v/v?as the solvent,in the presence of potassium phosphate at45?.2.A series of new palladium???complexes bearing bulky azole ligands were designed and synthesized.The structures of these complexes were characterized by nuclear magnetic resonance and X-ray single crystal diffraction.All these complexes,as pre-catalysts,have high catalytic efficiency for the Suzuki-Miyaura cross-coupling reactions of sterically hindered aryl chlorides with arylboronic acids and good to high yields are obtained with low catalysts loadings?0.1 mol%?,using water and isopropanol?1:1,v/v?as the solvent,in the presence of potassium phosphate at 45?.3.A series of bromotrihalomethylpyrrolidine derivatives were synthesized by a novel rhodium?I?-catalyzed cascade radical cyclization of 1,6-enynes with Br-CX₃?X=Cl,Br?.A variety of bromine-containing trihalomethylated pyrrolidines were obtained with a 5 mol%catalyst loading in the presence of sodium acetate and DPEPhos at 100?,using dioxane as the solvent.Meanwhile,a possible radical pathway is proposed and verified by experiment.