Amine Compounds Of Rare Earth Chloride And Rare Earth Silicon Ch Bond Activation

Organometallic reaction is most important and effective tool to achieve the atomic economy,simplicity of reaction procedure,mild reaction condition and environmental friendliness.Lanthanide elements lie inâ…¢B in the periodic table,which is the largest family.Lanthanide elements have a lot of different features from other transition metal counterparts,such as larger ionic radius,high coordination number,and unique electronic arrangement.At the same time their reactivity can be tuned by "lanthanide contract effect".In addition,rare earths are low-cost and low toxic.It is well-known that China possesses the resource advantage in rare earth.China has more than 50% of the world rare earth industrial reserves and produces and sells over 80 percent of rare earth products in the world market,so the development of application of rare earths in organic synthesis is very significant and urgent.This dissertation describes some new methods for the formation of carbon-carbon and carbon-heteroatom bonds catalyzed by simple lanthanide compounds like lanthanide trichloride and bis(trimethylsilyl)amide compounds.Firstly,we represent a new strategy for controlling the preferred depronotation of 1,3-dicarbonyl compounds to 1,3,3'-triketone by coordination of lanthanide trichloride with 1,3-dicarbonyl compounds,by which a general and highly efficient LnCl₃-catalyzed intra- and intermolecular catalytic system for C-acylation of 1, 3-dicarbonyl compounds and malononitrile with acid chlorides has been developed, giving moderate to excellent yields under mild conditions.This is the first catalytic example of such reactions.This method provides significant advantages in cost, tolerance of functional groups and simplicity of operation by obviating the use of strong bases and stoichiometric amounts of Lewis acids.Furthermore,the present catalyst is readily recovered and reused at least seven times for such reaction without visible loss of catalytic activity.ln addition,by applying this protocol as the key step, 3,5-disubstituted-lH-pyrazole-4-carboxylate can easily be synthesized in high yields in a one-pot procedure.Significantly,it is found that the entioselective preparation of 1,3,3'-triketone could be carried out,if LnCl₃ is replaced by Cp₂GdCl and with the presence of chiral ligand S,S-Binol.The ee value can be up to 95%.Furthermore,we find that lanthanide trichloride also catalyze the acylation of 1,3-dicarbonyl compounds with sulfonyl chloride in the presence of DABCO.Next,we discover that lanthanide trichloride can catalyze the Glaser coupling reaction in the presence of additive triphenylphosphine oxide and iodine.This is a first example of lanthanide-catalyzed Glaser coupling reaction,which expands the application of lanthanide trichloride in organic synthesis.Finally,mild and highly selective Ln[N(SiMe₃)₂]₃/n-BuNH₂ catalyzed addition of terminal alkynes to nitriles has been established,revealing a novel reactivity pattern of alkynes with nitriles and providing a new and economical route to conjugated ynones.It is first time that the construction of a conjugated ynone framework can be achieved from nitriles by a hydroalkynylation/hydrolysis sequence. The conversion provides a new,economical and mild protocol for the synthesis of conjugated ynones.