نتایج جستجو برای: olefin

تعداد نتایج: 2960  

2015
Karol Grela

Five years have passed since the first publication of the Thematic Series on Olefin Metathesis in the Beilstein Journal of Organic Chemistry [1]. During these years the research continued to progress at full speed. Astute readers of this Thematic Series, as well as readers of the recent books devoted to olefin metathesis [2,3], can easily see that a great number of studies in this field have ad...

Journal: :Chemistry 2013
Ruud G E Coumans Johannes A A W Elemans Alan E Rowan Roeland J M Nolte

We describe the synthesis of a series of interlocked structures from porphyrin-glycoluril cage compounds and bis(olefin)-terminated viologens by an olefin-metathesis protocol. The length of the chain connecting the olefin substituents with the viologen has a marked effect on the products of the ring-closure reaction. Long chains give [2]- and [3]catenane structures, whereas short chains give a ...

2016
Chandika D. Ramful Katherine N. Robertson Kai E. O. Ylijoki

The title compound, [Co(C10H15)(C2H4)2], was prepared by Na/Hg reduction of [Co2(C10H15)2(μ-Cl)2] in THF under an ethyl-ene atmosphere and crystallized from pentane at 193 K. The Co-C(olefin) bonds have an average length of 2.022 (2) Å, while the Co-C(penta-dien-yl) bonds average 2.103 (19) Å. The olefin C=C bonds are 1.410 (1) Å. The dihedral angle between the planes defined by the cyclo-penta...

2017
Julian C Lo Dongyoung Kim Chung-Mao Pan Jacob T Edwards Yuki Yabe Jinghan Gui Tian Qin Sara Gutiérrez Jessica Giacoboni Myles W Smith Patrick L Holland Phil S Baran

This Article details the development of the iron-catalyzed conversion of olefins to radicals and their subsequent use in the construction of C-C bonds. Optimization of a reductive diene cyclization led to the development of an intermolecular cross-coupling of electronically-differentiated donor and acceptor olefins. Although the substitution on the donor olefins was initially limited to alkyl a...

2003

Olefin metathesis polymerization, in particularly ring-opening metathesis polymerization (ROMP), has been a popular topic of modern research. Two other types are acyclic diene metathesis polymerization (ADMET) and cyclopolymerization of diynes. To date, there has been no report on a metathesis polymerization utilizing more than one metathesis process. Herein, the concept of multiple olefin meta...

2014
Shane L. Mangold Daniel J. O’Leary Robert H. Grubbs

Olefin metathesis has emerged as a promising strategy for modulating the stability and activity of biologically relevant compounds; however, the ability to control olefin geometry in the product remains a challenge. Recent advances in the design of cyclometalated ruthenium catalysts has led to new strategies for achieving such control with high fidelity and Z selectivity, but the scope and limi...

2015
Shane L. Mangold Robert H. Grubbs

Macrocyclic compounds occupy an important chemical space between small molecules and biologics and are prevalent in many natural products and pharmaceuticals. The growing interest in macrocycles has been fueled, in part, by the design of novel synthetic methods to these compounds. One appealing strategy is ring-closing metathesis (RCM) that seeks to construct macrocycles from acyclic diene prec...

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
Zachary D. Pozun Kelly Tran Anna Shi Ryan H. Smith Graeme Henkelman

The majority of nanocomposite olefin/paraffin separation membranes use silver nanoparticles or silver ions as the olefin binding agent. In this theoretical study, we characterize the olefin interaction with silver nanoparticles and show that silver is special in that it chemisorbs ethylene more weakly than other metals. Some variation with particle size is found; small 79 atom nanoparticles ten...

2015
Cheng-Liang Zhu Jun-Shan Tian Zhen-Yuan Gu Guo-Wen Xing Hao Xu

An iron-catalyzed enantioselective and diastereoselective intramolecular olefin aminochlorination reaction is reported (ee up to 92%, dr up to 15 : 1). In this reaction, a functionalized hydroxylamine and chloride ion are utilized as nitrogen and chlorine sources, respectively. This new method tolerates a range of synthetically valuable internal olefins that are all incompatible with existing a...

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