Active Indenyl-Phosphine Ligands:Synthesis And Application In C-C Coupling Reaction

Carbon-carbon bonds as the most basic units to construct organic compounds,such as drugs,natural products,dyes and the luminescent materials.Transition metals catalyzed coupling reactions are used as the main methods to form carbon-carbon bonds.Palladium has been the most widely used catalyst in urrently reported methods,such as Ullmann reaction,Suzuki-Miyaura,Heck,Stille and Sonogashira cross-coupling reactions.There is a great demand for palladium to synthesize chemical compounds containing carbon carbon bonds,but the palladium content in the earth's crust is very limited.Therefore,there are only two choices:the first one is to replace palladium catalyst by the other cheap metals,another one is to reduce inventory of palladium in the catalytic reaction.Some cheap metals,such as Fe,Co,Ni,Cu have been reported recently to replace the palladium as catalyst,but their applicability is limited.Our team have been synthesized many efficient indene phosphine ligands,and we found the activity of ligands in catalytic systems has a great influence on the catalytic effect.Based on the above background,this article mainly discussed the highly active indene-based phosphine ligands catalyze Suzuki-Miyaura cross-coupling reactions.Specific content is as follows:1.An easily available atalytic system[Pd(OAc)2/(2-(anthracen-9-yl)-1H-inden-3-yl)dicyclohexylphosphine/toluene/iPrOH/water]was developed,which shows high catalytic activity in the Suzuki-Miyaura cross-coupling reactions of a diverse array of aryl and heteroaryl chlorides with Pd loadings down to levels of 100 ppm.2.We synthesized seven new indene-based phosphine ligands L4-L10 from some cheap raw materials.Their structures were characterized by 1H NMR,13C NMR,31P NMR.And their structures were further confirmed by X-ray diffraction techniques,except for the ligand L9.In addition,we studied the activities of seven novel ligands used as palladium-catalyzed reactions to form C-C bonds.