A Convenient Method for the Efficient Removal of Ruthenium Byproducts Generated during Olefin Metathesis Reactions

Ahn, Yu Mi; Yang, Kyoung Lang; Georg, Gunda I.

doi:10.1021/ol010045k

Cited by 198 publications

(118 citation statements)

References 15 publications

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“…or 50 equiv. phosphine oxide with dimethylsulfoxide 24 , oxidation using Pb(OAc) 4 28 , purification based on monolithic materials 29 or using chelating compounds that assist with the extraction of the residue (mercaptonicotinic acid 30,31 and cystine 32 ). [Ru]…”

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confidence: 99%

Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

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In living ring-opening metathesis polymerization (ROMP), a transition-metal-carbene complex polymerizes ring-strained olefins with very good control of the molecular weight of the resulting polymers. Because one molecule of the initiator is required for each polymer chain, however, this type of polymerization is expensive for widespread use. We have now designed a chain-transfer agent (CTA) capable of reducing the required amount of metal complex while still maintaining full control over the living polymerization process. This new method introduces a degenerative transfer process to ROMP. We demonstrate that substituted cyclohexene rings are good CTAs, and thereby preserve the 'living' character of the polymerization using catalytic quantities of the metal complex. The resulting polymers show characteristics of a living polymerization, namely narrow molecular-weight distribution, controlled molecular weights and block copolymer formation. This new technique provides access to well-defined polymers for industrial, biomedical and academic use at a fraction of the current costs and significantly reduced levels of residual ruthenium catalyst. In olefin metathesis reactions, olefinic bonds are rearranged with the help of a transition-metal catalyst 1,2 . In the early days following the discovery of this reaction, ill-defined catalysts 3 were used to carry out this transformation. After Herisson and Chauvin 4 had proposed a reaction mechanism, the olefin metathesis reaction was better understood and soon gained much popularity. Typical catalysts used for olefin metathesis reactions include those based on ruthenium (developed mainly by the Grubbs group 5 ), tungsten and molybdenum (developed mainly by the Schrock group 6 ). Owing to the low oxophilicity of ruthenium compared to those of molybdenum and tungsten, the ruthenium metathesis catalysts (commonly known as Grubbs' catalysts) are more tolerant towards many polar functional groups and residual impurities, as well as to water 7 . Therefore, these catalysts are the catalysts of choice in highly functional organic chemistry transformations as well as for the majority of metathesis polymerizations carried out today. Catalysts G1 (first generation) and G3 (third generation) are the most widely used ruthenium initiators for ring-opening metathesis polymerization (ROMP). In comparison to the G1 initiator, the third-generation catalyst G3 exhibits very fast initiation and propagation rates, and thereby gives polymers with very narrow dispersities and an excellent control over their molecular weights. Owing to its superior stability as well as the favourable polymerization kinetics, the third-generation Grubbs' catalyst G3 was used for this work. ROMP is a polymerization technique that uses the metathesis of cyclic olefins to synthesize linear polymers. Depending on the structure of the monomer, such polymerizations can be controlled perfectly to give polymers with a narrow molecular weight distribution and a controlled average molecular weight. Ring-strained monomers, li...

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confidence: 99%

Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

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“…For example, when diethyl diallylmalonate is subjected to ring-closing metathesis (RCM) using 5 mol % 2 (Table 1), the [17,24,25,[34][35][36] Olefin Metathesis…”

Section: Problems Caused By Ruthenium Contamination In Natural or Commentioning

confidence: 99%

Sustainable Concepts in Olefin Metathesis

et al. 2007

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Ruthenium-catalyzed olefin metathesis reactions represent an attractive and powerful transformation for the formation of new carbon-carbon double bonds. This area is now quite familiar to most chemists as numerous catalysts are available that enable a plethora of olefin metathesis reactions. Nevertheless, with the exception of uses in polymerization reactions, only a limited number of industrial processes use olefin metathesis. This is mainly due to difficulties associated with removing ruthenium from the final products. In this context, a number of studies have been carried out to develop procedures for the removal of the catalyst or the products of catalyst decomposition, however, none are universally attractive so far. This situation has resulted in tremendous activity in the area dealing with supported or tagged versions of homogeneous catalysts. This Review summarizes the numerous studies focused on developing cleaner ruthenium-catalyzed metathesis processes.

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“…The RCM key step was readily performed under Ahn's conditions [27], i.e. with Grubbs catalyst of second generation (5 mol%), in diluted solution of 10 (5 mM in DCM), at room temperature.…”

Section: Synthesis (Scheme 3)mentioning

confidence: 99%

Novel Large‐Ring 1,3‐Bridged 2‐Azetidinones as Potential Inhibitors of Penicillin‐Binding Proteins

2009

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a b s t r a c tThe relationship between angular strain and (re)activity of bicyclic 2-azetidinones is still an open question of major concern in the field of penicillin antibiotics. Our study deals with original 13-membered-ring 1,3-bridged 2-azetidinones related to the carbapenem family, and featuring a ''planar amide'' instead of the ''twisted amide'' typical of penam derivatives. The bicycles 11 and 12 were obtained from acetoxy-azetidinone 7, via the key-intermediate 10, by using the RCM (ring closing metathesis) strategy. Theoretical predictions and experimental results of hydrolysis showed that the large bicycle 12, endowed with high conformational flexibility, is more reactive than the bicycle 11, including a C]C bond of E configuration, and the monocyclic 2-azetidinone precursor 10. The processing of 2-azetidinones 10-12 in the active site of serine enzymes has been computed by ab initio methods, considering three models. Due to geometrical parameters of the enzymic cavity (nucleophilic attack from the a-face), precursor 10 was predicted more active than 11 and 12 in the acylation step by Ser-OH.Indeed, bicycles 11 and 12 are modest inhibitors of PBP 2a , while 10 is a good to excellent inhibitor of PBP 2a and R39 bacterial enzymes.

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A Convenient Method for the Efficient Removal of Ruthenium Byproducts Generated during Olefin Metathesis Reactions

Cited by 198 publications

References 15 publications

Catalytic living ring-opening metathesis polymerization

Catalytic living ring-opening metathesis polymerization

Sustainable Concepts in Olefin Metathesis

Novel Large‐Ring 1,3‐Bridged 2‐Azetidinones as Potential Inhibitors of Penicillin‐Binding Proteins

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