Research On C-H Activation Of Pyridines Catalyzed By Organic Rare-earth Catalysts

In recent decades,an activation of C-H bond of substrate has fascinated more and more organic chemistry researchers by virtue of its high atomic efficiency and low toxicity,incontrast to the cross-coupling reactions,which conforms to the concept of green chemistry.In this regard,catalyst based on rare-earth metal exhibites the unique advantages of their own,such as simple reaction conditions,wide range of catalyst sources,easy availability,good selectivity,and high yield of isolated product.In this paper,the recent progress in C-H activation reaction catalyzed metal-based complexes including transition metal and rare-earth metal complexes has been reviewed.In addition,the synthesis of some mono(phosphinoamide)organo-rare-earth complexes and their applications in catalytic C-H bond activation reactions are also presented.The works are as follows:(1)The six rare-earth bisalkyl complexes supported by only one phosphinoamide ligand(?2-N-P)Ln(CH2C6H4NMe2-o)2(Ln=Sc,Y,and Lu)were synthesized for the first time via acid-based reaction of various phosphinoamines(NH-P1,NH-P2,NH-P3,NH-P4)and Ln(CH2C6H4NMe2-o)3 in THF.Their structures were characterized by 1H NMR,13C NMR,31P NMR spectra,and single crystal X-ray diffraction analysis.(2)The C(sp2)-H bond of pyridines addition to olefins catalyzed by the 1:1 combination of(?2-N-P1)Sc(CH2C6H4NMe2-o)2 and B(C6F5)3 was investigated with chlorobenzene as the solvent,the amount of catalyst being of 4.0 mmol%,and the reaction temperature being of 100?.The isolated yields of additive product of pyridines were in the range of 61?98%.(3)The C(sp3)-H activation reaction between pyridines and olefins was also investigated in chlorobenzene at 100 0C,using(?-N-P1)Y(CH2C6H4NMe2-o)2(2.0%mmol)as a catalyst and[Ph3C][B(C6F5)4](2.0 mmol%)as an activator.It was found that the isolated yield of the additive products were in the range of 53?99%.