- Catalyst versus Substrate Control of Forming (E)-2-Alkenes from 1-Alkenes Using Bifunctional Ruthenium Catalysts
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Here we examine in detail two catalysts for their ability to selectively convert 1-alkenes to (E)-2-alkenes while limiting overisomerization to 3- or 4-alkenes. Catalysts 1 and 3 are composed of the cations CpRu(κ2-PN)(CH3CN)+ and Cp?Ru(κ2-PN)+, respectively (where PN is a bifunctional phosphine ligand), and the anion PF6-. Kinetic modeling of the reactions of six substrates with 1 and 3 generated first- and second-order rate constants k1 and k2 (and k3 when applicable) that represent the rates of reaction for conversion of 1-alkene to (E)-2-alkene (k1), (E)-2-alkene to (E)-3-alkene (k2), and so on. The k1:k2 ratios were calculated to produce a measure of selectivity for each catalyst toward monoisomerization with each substrate. The k1:k2 values for 1 with the six substrates range from 32 to 132. The k1:k2 values for 3 are significantly more substrate-dependent, ranging from 192 to 62 000 for all of the substrates except 5-hexen-2-one, for which the k1:k2 value was only 4.7. Comparison of the ratios for 1 and 3 for each substrate shows a 6-12-fold greater selectivity using 3 on the three linear substrates as well as a >230-fold increase for 5-methylhex-1-ene and a 44-fold increase for a silyl-protected 4-penten-1-ol substrate, which are branched three and five atoms away from the alkene, respectively. The substrate 5-hexen-2-one is unique in that 1 was more selective than 3; NMR analysis suggested that chelation of the carbonyl oxygen can facilitate overisomerization. This work highlights the need for catalyst developers to report results for catalyzed reactions at different time points and shows that one needs to consider not only the catalyst rate but also the duration over which a desired product (here the (E)-2-alkene) remains intact, where 3 is generally superior to 1 for the title reaction.
- Paulson, Erik R.,Delgado, Esteban,Cooksy, Andrew L.,Grotjahn, Douglas B.
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supporting information
p. 1672 - 1682
(2019/01/04)
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- General catalyst control of the monoisomerization of 1-alkenes to trans -2-alkenes
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After searching for the proper catalyst, the dual challenges of controlling the position of the double bond, and cis/trans-selectivity in isomerization of terminal alkenes to their 2-isomers are finally met in a general sense by mixtures of (C5Me5)Ru complexes 1 and 3 featuring a bifunctional phosphine. Typically, catalyst loadings of 1 mol % of 1 and 3 can be employed for the production of (E)-2-alkenes at 40-70 C. Catalyst comprising 1 and 3 avoids more than any other known example the thermodynamic equilibration of alkene isomers, as the trans-2-alkenes of both nonfunctionalized and functionalized alkenes are generated.
- Larsen, Casey R.,Erdogan, Gulin,Grotjahn, Douglas B.
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supporting information
p. 1226 - 1229
(2014/02/14)
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- Decenal mixtures and their use in perfume compositions
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The present invention relates to a novel decenal mixture and the incorporation and use of this mixture as a fragrance material. The novel decenal mixture contains decenals that are represented by the formula set forth below: wherein the broken line represents one double bond and two single bonds.
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Page/Page column 6
(2013/06/27)
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- Nickel phthalocyanine assisted highly efficient and selective carbonyl reduction in polyethylene glycol-400
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Nickel phthalocyanine with polyethylene glycol- 400 is described as a reusable green catalytic system for highly chemo- and regioselective reduction of carbonyl compounds to corresponding alcohols at room temperature. The catalytic system showed wide substrate scope covering aromatic, hetero aromatic and aliphatic carbonyl compounds with high turnover number and frequency. In the present study, 1,3- and 1,4-benzenedicarbaldehydes have been regioselectively reduced to corresponding alcohols for the first time. The catalyst was reused up to seven times without any significance loss in activity. Springer Science+Business Media, LLC 2012.
- Verma, Praveen Kumar,Sharma, Upendra,Kumar, Neeraj,Bala, Manju,Kumar, Vishal,Singh, Bikram
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experimental part
p. 907 - 913
(2012/10/07)
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- Supramolecular catalyst for aldehyde hydrogenation and tandem hydroformylation-hydrogenation
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The chemoselective reduction of aldehydes and the tandem hydroformylation-hydrogenation of terminal alkenes are possible with a supramolecular catalyst that operates by a novel mechanism involving substrate activation by hydrogen bonding and subsequent metalligand bifunctional hydrogenation (see scheme).
- Diab, Lisa,Smejkal, Tomas,Geier, Jens,Breit, Bernhard
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supporting information; experimental part
p. 8022 - 8026
(2010/02/28)
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- Bidentate ligands by self-assembly through hydrogen bonding: A general room temperature/ambient pressure regioselective hydroformylation of terminal alkenes
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The 6-DPPon (1)/rhodium catalyst allows for the first time a room temperature/ambient pressure regioselective hydroformylation of terminal alkenes with low catalyst loadings in good activity. The generality of this catalyst under these conditions was demonstrated for a wide range of structurally diverse alkenes equipped with many important functional groups. Thus, this practical and highly selective hydroformylation protocol, which omits the need for special pressure equipment, should find wide application in organic synthesis.
- Seiche, Wolfgang,Schuschkowski, Alexander,Breit, Bernhard
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p. 1488 - 1494
(2007/10/03)
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- New and simple syntheses of the attractants of the female melon fly, dacus cucurbitee
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The attractant of the female melon fly, (E)-6-nonenyl acetate, and the two analogs, (E)-7-dodecenyl acetate and (E)-7-decenyl acetate were synthesized via hydrozirconation to control the regioselective coupling reactions and resulted in good yields.
- Yen, Yao-Pin,Chen, Pao-Hsing
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- Short and stereoselective syntheses of pheromone components of Aproaerema modicella
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Efficient syntheses of pheromone components of Aproaerema modicella starting from a common intermediate 7-octyn-1-ol is described.
- Yadav,Chandrasekhar,Kache
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p. 4035 - 4043
(2007/10/03)
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