نتایج جستجو برای: metathesis

تعداد نتایج: 2718  

2010
Miwako Mori

Abstract: Olefin metathesis using ruthenium carbene complexes is a useful method in synthetic organic chemistry. Enyne metathesis is also catalyzed by these complexes and various carboand heterocycles could be synthesized from the corresponding enynes. Dienyne metathesis, cross enyne metathesis and ring-opening enyne metathesis have been further developed. Various complicated compounds, such as...

Journal: :Journal of the American Chemical Society 2003
Arnab K Chatterjee Tae-Lim Choi Daniel P Sanders Robert H Grubbs

In recent years, olefin cross metathesis (CM) has emerged as a powerful and convenient synthetic technique in organic chemistry; however, as a general synthetic method, CM has been limited by the lack of predictability in product selectivity and stereoselectivity. Investigations into olefin cross metathesis with several classes of olefins, including substituted and functionalized styrenes, seco...

2011
Didier Astruc Abdou K Diallo Sylvain Gatard Liyuan Liang Cátia Ornelas Victor Martinez Denise Méry Jaime Ruiz

The interplay between olefin metathesis and dendrimers and other nano systems is addressed in this mini review mostly based on the authors' own contributions over the last decade. Two subjects are presented and discussed: (i) The catalysis of olefin metathesis by dendritic nano-catalysts via either covalent attachment (ROMP) or, more usefully, dendrimer encapsulation - ring closing metathesis (...

2017
T. Patrick Montgomery Adam M. Johns Robert H. Grubbs

Olefin metathesis is a prevailing method for the construction of organic molecules. Recent advancements in olefin metathesis have focused on stereoselective transformations. Ruthenium olefin metathesis catalysts have had a particularly pronounced impact in the area of stereoselective olefin metathesis. The development of three categories of Z-selective olefin metathesis catalysts has made Z-ole...

Journal: :Journal of the American Chemical Society 2015
Ho-Keun Lee Ki-Taek Bang Andreas Hess Robert H Grubbs Tae-Lim Choi

We demonstrated tandem ring-opening/ring-closing metathesis (RO/RCM) polymerization of monomers containing two cyclopentene moieties and postmodification via insertion polymerization. In this system, well-defined polymers were efficiently formed by tandem cascade RO/RCM reaction pathway. Furthermore, these polymers could be transformed to new A,B-alternating copolymers via a sequential cross me...

2007
Miwako Mori

Since the molybdenum and ruthenium carbene complexes 1a and 1b were discovered by Schrock and Grubbs in 1990 and 1992, synthetic organic chemistry has progressed with the use of these complexes as the catalyst for olefin metathesis. It was found that the ruthenium carbene complex was also effective for enyne metathesis, which occurs between an alkene and an alkyne. Intramolecular enyne metathes...

2010
Julia Wappel César A Urbina-Blanco Mudassar Abbas Jörg H Albering Robert Saf Steven P Nolan Christian Slugovc

The aims of this contribution are to present a straightforward synthesis of 2(nd) generation Hoveyda-type olefin metathesis catalysts bearing bromo and iodo ligands, and to disclose the subtle influence of the different anionic co-ligands on the catalytic performance of the complexes in ring opening metathesis polymerisation, ring closing metathesis, enyne cycloisomerisation and cross metathesi...

Journal: :Journal of the American Chemical Society 2008
Matthew Carnes Daniela Buccella Theo Siegrist Michael L Steigerwald Colin Nuckolls

Here we describe the metathesis reactions of a strained eight-membered ring that contains both alkene and alkyne functionality. We find that the alkyne metathesis catalyst produces polymer through a ring-opening alkyne metathesis reaction that is driven by the strain release from the monomer. The strained monomer provides unusual reactivity with ruthenium-based alkene metathesis catalysts. We i...

Journal: :Tetrahedron 2009
Kyu Ok Jeon Dinesh Rayabarapu Alan Rolfe Kelly Volp Iman Omar Paul R Hanson

The development of a ring-opening metathesis/ring-closing metathesis/cross metathesis (ROM-RCM-CM) cascade strategy to the synthesis of a diverse collection of bi- and tricyclic sultams is reported. In this study, functionalized sultam scaffolds derived from intramolecular Diels-Alder (IMDA) reactions undergo metathesis cascades to yield a collection tricyclic sultams. Additional appendage base...

Journal: :Chemical communications 2014
David J Nelson Simone Manzini César A Urbina-Blanco Steven P Nolan

While the fundamental series of [2+2]cycloadditions and retro[2+2]cycloadditions that make up the pathways of ruthenium-catalysed metathesis reactions is well-established, the exploration of mechanistic aspects of alkene metathesis continues. In this Feature Article, modern mechanistic studies of the alkene metathesis reaction, catalysed by well-defined ruthenium complexes, are discussed. Broad...

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