The Application of Non-metallocene Organometallic Complexes Based on Rare Earth Metal in Organic Synthesis Reaction and Polymer Synthesis Reaction

Author:Cai Gui Long

Supervisor:li xiao fang


Degree Year:2017





Non-metallocene rare-earth organometallic compounds have a series of unique characteristics(for example:high positive electricity,stable valence state(+3),high coordination numbers,etc.).The last twenty years have witnessed rapid developments of these compounds which have displayed high reactivity,high selectivity and single active specie property in the research on reaction mechanism of organic synthesis and olefins polymerizations.It has been an important research area of non-metallocene rare-earth organometallic compounds,for one thing,the cross-coupling reactions using non-metallocene rare-earth organometallic compounds are far from being well developed;for another thing,there are still great challenges in the non-metallocene rare-earth organometallic compounds catalyzed coordination polymerization reaction of polar monomer with both high activity and high selectivity.In this thesis,two major aspects have been accomplished:First,a series of functional organic molecules have been synthesized via cross-coupling reactions using trialkyl rare-earth organometallic compounds as nucleophilic reagents;Then,several non-metallocene rare-earth organometallic compounds have been designed,synthesized,and used in the polymerization of polar olefin monomer 2-vinyl pyridine.The specific research contents are as follows:(1)A highly efficient C(sp3)-C(sp2)cross-coupling of Ln(CH2SiMe3)3(THF)2(Ln=Y,Sc,Lu;0.33 eqiv)with aryl bromides has been developed for the construction of functionalized benzyltrimethylsilanes with excellent yields(up to 99%).This reaction was conducted at room temperature in the presence with very low catalyst loading(0.5mol%Pd2(dba)3/4XPhos)and exhibited broad substrate scope.(2)Pd-Catalyzed C(sp3)-C(sp2)cross-coupling of Y(CH2SiMe3)3(THF)2(0.33equiv)with vinyl bromides or triflates has been developed for efficient synthesis of various allyltrimethylsilanes(yields up to 99%).The cross-coupling reaction was conducted at room temperature with low catalyst loading of either Pd(PPh3)4(1 mol%)or Pd(PPh3)2Cl2(1 mol%)and exhibited high efficiency and broad substrate scope.(3)A series of polysubstituted olefin compounds have been constructed by one-pot or step-by-step reaction using Y(CH2SiMe3)3(THF)2 as a novel nucleophilic one-carbon synthon for the synthesis of complex compounds.In combination with the cross-coupling by the Lewis acid(YBr3 or Y(OTf)3)catalyzed Hosomi-Sakurai reaction,a novel three-component one-pot cascade reaction was then accomplished to deliver homoallylic alcohols and ethers with high regioselectivity and diastereoselectivity.The stepwise reaction was carried out by the reaction of allyltrimethylsilanes with acetal or aryl iodide under strong Lewis acid(TiCl4)catalysts.This method can be used for efficient synthesis of polysubstituted olefins.(4)Four non-metallocene rare-earth organometallic compounds(L1-Ln,L2-Ln,L3-Ln and L4-Ln)were synthesized via the reaction between phenolic hydroxylamine ligands and Ln(CH2SiMe3)3(THF)2(Ln=Y,Sc,Lu).These complexes were subsequently used in the polymerization of polar monomer 2-vinylpyridine.The results showed that such complexes are efficient catalyst in the synthesis of isotactic([mmmm]=67%),high molecular weighted(42.4×104 g/mol)poly-2-vinylpyridine.It is worth noting that the catalysts have high activity over a wide temperature range,and in particular,complex L1-Sc has high activity even at 150℃.