Investigations into Asymmetric Post-Metallocene Group 4 Complexes for the Synthesis of Highly Regioirregular Polypropylene
摘要:
A series of asymmetric post-metallocene group 4 complexes based on a modular anilide(pyridine)phenoxide framework have been synthesized and tested for propylene polymerization activity. These complexes, upon activation with methylaluminoxane (MAO), produce highly regioirregular and stereoirregular polypropylene with moderate to good activities. Surprisingly, modification of the anilide R-group substituent from 1-phenethyl to benzyl or adamantyl did not significantly change the polymer microstructure as determined by C-13 NMR spectroscopy. Although polymer molecular weights and poly-dispersities vary with propylene pressure, temperature, and activator, regio- and stereoirregularity were also found to be relatively insensitive to these variables. When the polymerization is conducted at 70 degrees C under dihydrogen, partial decomposition to a highly active catalyst that produces an isotactic microstructure occurs; the undecomposed catalyst continues to produce highly regioirregular and stereoirregular polypropylene under these conditions.
Pd-Catalyzed Aryl Amination Mediated by Well Defined, N-Heterocyclic Carbene (NHC)–Pd Precatalysts, PEPPSI
作者:Michael G. Organ、Mirvat Abdel-Hadi、Stephanie Avola、Igor Dubovyk、Niloufar Hadei、Eric Assen B. Kantchev、Christopher J. O'Brien、Mahmoud Sayah、Cory Valente
DOI:10.1002/chem.200701621
日期:2008.3.7
Pd-N-heterocyclic carbene (NHC)-catalyzed Buchwald-Hartwig amination protocols mediated by Pd-PEPPSI precatalysts is described. These protocols provide access to a range of hindered and functionalized drug-like aryl amines in high yield with both electron-deficient and electron-rich aryl- and heteroaryl chlorides and bromides. Variations in solvent polarity, base and temperature are tolerated, enhancing
Palladium-catalyzed amination of isomeric dihalobenzenes with 1- and 2-aminoadamantanes
作者:A. D. Averin、M. A. Ulanovskaya、V. V. Kovalev、A. K. Buryak、B. S. Orlinson、I. A. Novakov、I. P. Beletskaya
DOI:10.1134/s1070428010010069
日期:2010.1
Palladium-catalyzed amination of isomeric bromochloro- and dibromobenzenes with 1- and 2-aminoadamantanes was studied. The best yields of the corresponding monoamination products were obtained in the reactions of 2-aminoadamantane with bromochlorobenzenes. The arylation of 1-aminoadamantane was successful in the presence of donor phosphine ligand. The amination of o- and m-dibromobenzenes was strongly complicated by formation of diamination products. Conditions ensuring predominant formation of the latter were found. The arylation of 2-aminoadamantane was accompanied by oxidation of the initial amine and reduction of aryl halide.