Propylene Polymerization with Unbridged Metallocenes: Ligand Effects on the Selectivity for Elastomeric Polypropylene
作者:Jennifer L. Maciejewski Petoff、Michael D. Bruce、Robert M. Waymouth、Athar Masood、Tapan K. Lal、Roger W. Quan、Steven J. Behrend
DOI:10.1021/om9706119
日期:1997.12.1
elastomeric polypropylene with a stereoblock microstructure. In an effort to experimentally explore the importance of the 2-arylindene ligand in producing these materials, a series of catalysts was investigated that differed significantly from the parent ligand architecture. In particular, we sought to examine the influence of ligand aryl stacking on the polymerization behavior of these metallocenes. We discovered
Gold(I)-Catalyzed Highly Enantioselective [4 + 2]-Annulations of Cyclopentadienes with Nitrosoarenes via Nitroso-Povarov versus Oxidative Nitroso-Povarov Reactions
作者:Prakash D. Jadhav、Jia-Xuan Chen、Rai-Shung Liu
DOI:10.1021/acscatal.0c01293
日期:2020.5.15
gold-catalyzed highlyenantioselective nitroso-Povarov reactions between cyclopentadienes and nitrosoarenes in cold dichloroethane, in which nitrosoarenes serve as 4π-electron donors and cyclopentadienes as 2π-donors. High enantioselectivity has been achieved for substrates over a wide scope. With the same chiral catalyst, nitroso-4-fluorobenzenes in these reactions under DCM/THF/water/air led to oxidative nitroso-Povarov
Gold(I)-Catalyzed Highly Diastereo- and Enantioselective Constructions of Bicyclo[3.2.1]oct-6-ene Frameworks via (4 + 3)-Cycloadditions
作者:Sudhakar Dattatray Tanpure、Tung-Chun Kuo、Mu-Jeng Cheng、Rai-Shung Liu
DOI:10.1021/acscatal.1c04483
日期:2022.1.7
1]oct-6-ene frameworks involves gold-catalyzed (4 + 3)-cycloadditions between 2-(1-alkynyl)-2-alken-1-ones and substituted cyclopentadienes; diastereoselectivity (dr >25:1) and enantioselectivity (up to 99.9% ee) are achieved with a chiral gold catalyst. Our DFT calculations suggest a three-step ionic mechanism for the cycloadditions of gold-containing 1,3-dipoles with cyclopentadienes, in which an exo-spatial
Gold-Catalyzed Rearrangement of α-Carbonyl Cyclopropanes to Form 3-(Cyclopenta-1,3-dien-1-ylmethyl)oxindoles via a Postulated 1,5-Enolate Shift
作者:Amit Vijay Sasane、Tung-Chun Kuo、Mu-Jeng Cheng、Rai-Shung Liu
DOI:10.1021/acs.orglett.2c02117
日期:2022.7.22
Gold-catalyzed stereoselectivesynthesis of spirocyclopropyloxindolesfrom diazooxindoles and 1,2,4-substituted dienes is described. The aim of this work is to report a novel rearrangement of these spirocyclopropyloxindoles with a gold catalyst to yield 3-(cyclopenta-1,3-dien-1-ylmethyl)oxindoles. Our experimental data exclude a reversible process in the gold-catalyzed cyclopropanation. With DFT
Cooperative effects in binuclear zirconocenes: Their synthesis and use as catalyst in propene polymerization
作者:Stephan Jüngling、Rolf Müllhaupt、Herbert Plenio
DOI:10.1016/0022-328x(93)83145-l
日期:1993.11
The mono- and bis-cyclopentadienyl compounds 1-(Cp'')-4-(CH3)C6H4 (1) and 1, 4-(Cp'')(2)C6H4 (2) (Cp'' = 3,4-dimethylcyclopenta-1,3-diene-1-yl) have been synthesized. The reactions of the lithium salts of 1 and 2 with CpZrCl(3).dme (dme = dimethoxyethane) and Cp(*)ZrCl(3)(Cp(*) = C-5(CH3)(5)) yielded the mono- and bi-nuclear bridged zirconocenes 1-(Cp''ZrCpCl(2) )-4-(CH3)C6H4 (3), 1,4-(Cp''ZrCpCl(2))(2)C6H4 (4) and 1,4-(Cp''ZrCp(*)Cl(2))(2)C6H4 (5). When activated with methylaluminoxane (MAO), the mono- and bi-nuclear zirconocenes 3 and 4 catalyse the polymerization of propene. The influence of the catalyst composition on the polymerization kinetics and molecular weight is discussed.