20592-10-3Relevant articles and documents
Chiral indenes and group-4 metallocene dichlorides containing α- And β-pinenyl-derived ligand substituants: Synthesis and catalytic applications in polymerization and carboalumination reactions
Silver, Satu,Puranen, Arto,Sjoeholm, Rainer,Repo, Timo,Leino, Reko
, p. 1514 - 1529 (2005)
The synthesis and characterization of chiral bis(indenyl)zirconium dichlorides containing β-pinenyl-derived ligand substituents is reported. Unbridged metallocene complexes having the ∥(1S, 2S, 5S)-6,6- dimethylbicyclo[3.1.1]hept-2-yl]methyl)dimethylsilyl substituent in both 1- and 2-positions of the indenyl moiety were prepared and isolated in moderate to low yields by reaction of the corresponding indenyllithium salts with ZrCl 4 followed by work-up and crystallization procedures. The corresponding tetrahydroindenyl complexes were obtained in excellent yields by catalytic hydrogenation of the indenyl six-membered rings. In a complementary approach, a synthetic route to α-pinenyl-substituted indenyl ligand analogues was briefly evaluated, which however, suffered from low yields. Selected ss-pinenyl-substituted indenyl complexes were scanned as catalysts for the dehydropolymerization of phenylsilane upon activation with nBuLi, for polymerization of ethylene and propylene upon activation with methylalumlnoxane (MAO) as well as for enantioselective carboalumination of 1-octene with triethyland trimethylaluminum. The bis(indenyl) complexes catalyzed the carboalumination reaction, albeit only low yields (8-16%) and low enantioselectivities (ee = 0.5-10%) were obtained. The 2-substituted bis(indenyl)zirconocene/MAO catalyst system produced atactic low-molecular weight polypropylene with low polymerization activity whereas both 1-and 2-substituted complexes showed high activities in ethylene polymerization producing polyethylenes with high molecular weights (Mw > 440000).
Diastereoselective synthesis of functionally substituted alkene dimers and oligomers, catalysed by chiral zirconocenes
Kovyazin, Pavel V.,Abdullin, Il'giz N.,Parfenova, Lyudmila V.
, p. 144 - 152 (2018/11/21)
The research addresses the reaction of terminal alkenes and propene with AlR3 (R = Me, Et) in the presence of chiral Zr complexes, rac-[Y(η5-C9H10)2]ZrCl2 (Y = C2H4, SiMe2) or (NMI)2ZrCl2 (NMI- η5–neomenthylindenyl), and methylaluminoxane. The effect of reaction conditions, catalyst and trialkylalane structure on the substrate conversion and the reaction chemo- and stereoselectivity has been studied. The reaction predominantly goes via the stage of alkene methyl(ethyl)zirconation with subsequent introduction of substrate molecules into the Zr-C bond. As a result, a diastereoselective one-pot method for the synthesis of functionally substituted linear terminal alkene dimers and propene oligomers was developed.
Asymmetric alkene cycloalumination by AlEt3, catalyzed with neomenthylindenyl zirconium η5-complexes
Parfenova, Lyudmila V.,Kovyazin, Pavel V.,Tyumkina, Tatyana V.,Berestova, Tatyana V.,Khalilov, Leonard M.,Dzhemilev, Usein M.
, p. 19 - 25 (2013/02/21)
The paper is devoted to a study of the reaction of terminal alkene cycloalumination by AlEt3 catalyzed with neomenthylindenyl zirconium complexes (p-S)(p-S)-bis[η5-[1-[(1S,2S,5R)-2-isopropyl-5- methylcycloh-exyl]indenyl]]zirconium dichloride (1) or (p-S)-(η5- cyclopentadienyl)[η5-[1-[(1S,2S,5R)-2-isopropyl-5- methylcyclohexyl]indenyl]]zirconium dichloride (2). It was shown that alkene and catalyst structures, as well as solvent, affect the overall yield and enantiomeric excess of the reaction product - 3-alkylsubstituted aluminacyclopentanes. The reaction of terminal alkenes with AlEt3, catalyzed by complex 1, in hydrocarbon solvents gives predominantly S-enantiomers of cyclic organoaluminum compounds with enantiomeric excess up to 37%. Complex 2 shows smaller stereoinduction effect and provides R-enantiomers of aluminacyclopentanes with 6-26%ee. The effectiveness of selenium-containing derivatizing reagent (R)-2-phenylselenopropanoic acid for the enantiomeric excess estimation in β-alkyl-1,4-butanediols obtained from cyclic organoaluminum compounds was shown.
