- Photogeneration of a phosphonium alkylidene olefin metathesis catalyst
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Treatment of ruthenium carbide (H2IMes)(Cl)2(PCy 3)RuC (1) with the photoacid generator (PAG) [Ph3S][OTf] (3) under 254 nm light results in a highly efficient catalyst for ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) reactions. The reactions proceed via formation of the ruthenium phosphonium alkylidene complex [(H2IMes)(Cl)2Ru=C(H)PCy3][OTf] as the active catalytic species. In the case of ROMP of cycloalkenes, reactions do not require addition of PAG and protonation of 1 proceeds via allylic C-H bond activation of the substrate under UV light.
- Khalimon, Andrey Y.,Leitao, Erin M.,Piers, Warren E.
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- Rapidly initiating ruthenium olefin-metathesis catalysts
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Vacancies: Protonation of the ruthenium carbide compounds [Cl 2(L)(PR3)Ru≡C:] gives the 14-electron four-coordinate ruthenium phosphonium alkylidenes [Cl2(L)Ru= CH(PR3)]+[B(X)4]- (see scheme). These compounds which already have a vacant coordination site provide direct access to the active species in olefin metathesis catalysis and thus very fast initiation.
- Romero, Patricio E.,Piers, Warren E.,McDonald, Robert
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Read Online
- COMPOUNDS FOR SELECTIVE BINDING TO ESTROGEN RECEPTORS ALPHA/BETA RELATIVE TO GPER/GPR30
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The current invention is in the field of molecular biology/pharmacology and provides novel 3-oxabicyclo [3.3.1] nonene compounds and derivatives that modulate the effects of the classical estrogen receptors alpha and beta (ERalpha and ERbeta) with little to no biological or physiological effects on the G protein-coupled estrogen receptor GPER (also known as GPR30). These compounds may function as agonists and/or antagonists of one or more of the disclosed classical estrogen receptors.
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Page/Page column 44
(2021/03/05)
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- A Selective Ligand for Estrogen Receptor Proteins Discriminates Rapid and Genomic Signaling
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Estrogen exerts extensive and diverse effects throughout the body of women. In addition to the classical nuclear estrogen receptors (ERα and ERβ), the G protein-coupled estrogen receptor GPER is an important mediator of estrogen action. Existing ER-target
- Revankar, Chetana M.,Bologa, Cristian G.,Pepermans, Richard A.,Sharma, Geetanjali,Petrie, Whitney K.,Alcon, Sara N.,Field, Angela S.,Ramesh, Chinnasamy,Parker, Matthew A.,Savchuk, Nikolay P.,Sklar, Larry A.,Hathaway, Helen J.,Arterburn, Jeffrey B.,Oprea, Tudor I.,Prossnitz, Eric R.
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p. 1692 - 5,1702
(2019/11/28)
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- Catalytic intramolecular carbonyl-ene reaction with ketones: Evidence for a retro-ene process
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The ene-process with unsaturated ketones was catalyzed by Lewis acids such as bismuth or indium triflates. Unlike aldehydes, the reverse ene-process occurs with ketones, resulting in incomplete conversions, as shown by control experiments and analysis by ESI-MS.
- Tremel,Iacobucci,Massi,Olivero,Gal,Du?ach
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p. 7453 - 7458
(2015/09/02)
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- Synthesis of substituted cycloalkene-1,1-dicarboxylates via olefin metathesis in water
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A range of substituted cycloalkene-1,1-dicarboxylates was synthesized through olefin metathesis starting from readily available acylic malonate precursors in an efficient fashion. As a metathesis catalyst, a Grubbs II-type catalyst was used in these exper
- Tenbrink, Katharina,Kemker, Isabell,Schatz, Jürgen,Gr?ger, Harald
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- Fast olefin metathesis at low catalyst loading
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Reactions of the Grubbs 3rd generation complexes [RuCl2(NHC) (Ind)(Py)] (N-heterocyclic carbene (NHC)=1,3-bis(2,4,6- trimethylphenylimidazolin)-2-ylidene (SIMes), 1,3-bis(2,6- diisopropylphenylimidazolin)-2-ylidene (SIPr), or 1,3-bis(2,6- diisopropylphenylimidazol)-2-ylidene (IPr); Ind=3-phenylindenylid-1-ene, Py=pyridine) with 2-ethenyl-N-alkylaniline (alkyl=Me, Et) result in the formation of the new N-Grubbs-Hoveyda-type complexes 5 (NHC=SIMes, alkyl=Me), 6 (SIMes, Et), 7 (IPr, Me), 8 (SIPr, Me), and 9 (SIPr, Et) with N-chelating benzylidene ligands in yields of 50-75 %. Compared to their respective, conventional, O-Grubbs-Hoveyda complexes, the new complexes are characterized by fast catalyst activation, which translates into fast and efficient ring-closing metathesis (RCM) reactivity. Catalyst loadings of 15-150 ppm (0.0015-0.015 mol %) are sufficient for the conversion of a wide range of diolefinic substrates into the respective RCM products after 15 min at 50 °C in toluene; compounds 8 and 9 are the most catalytically active complexes. The use of complex 8 in RCM reactions enables the formation of N-protected 2,5-dihydropyrroles with turnover numbers (TONs) of up to 58 000 and turnover frequencies (TOFs) of up to 232 000 h-1; the use of the N-protected 1,2,3,6-tetrahydropyridines proceeds with TONs of up to 37 000 and TOFs of up to 147 000 h-1; and the use of the N-protected 2,3,6,7-tetrahydroazepines proceeds with TONs of up to 19 000 and TOFs of up to 76 000 h-1, with yields for these reactions ranging from 83-92 %. The tortoise and the hare: The use of diphenylalkylamino-based instead of phenyldialkylamino-based styrenes (see figure) leads to rapidly initiating precatalysts that enable very fast ring-closing metathesis reactions with turnover numbers of up to 58 000 and turnover frequencies of up to 232 000 h-1. Copyright
- Peeck, Lars H.,Savka, Roman D.,Plenio, Herbert
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p. 12845 - 12853
(2012/11/06)
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- Sequential catalysis: A metathesis/dihydroxylation sequence
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(Chemical Equation Presented) A real step-saver: A single ruthenium-carbene complex catalyzes a sequence of two reactions, namely, a metathesis reaction (ring-closing or cross metathesis) and subsequent dihydroxylation of the newly formed double bond. A v
- Beligny, Samuel,Eibauer, Stefan,Maechling, Simon,Blechert, Siegfried
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p. 1900 - 1903
(2007/10/03)
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- Structure-activity relationships and sub-type selectivity in an oxabicyclic estrogen receptor α/β agonist scaffold
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An oxabicyclic template for estrogen receptor α and β agonists has been identified which can be tuned to provide moderate levels of selectivity for either receptor sub-type. Structure-activity relationships within this phenol-substituted oxabicyclo[3.3.1]
- Hamann, Lawrence G.,Meyer, J. Hoyt,Ruppar, Daniel A.,Marschke, Keith B.,Lopez, Francisco J.,Allegretto, Elizabeth A.,Karanewsky, Donald S.
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p. 1463 - 1466
(2007/10/03)
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- Effects of Olefin Substitution on the Ring-Closing Metathesis of Dienes
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Ruthenium alkylidene 1 and molybdenum alkylidene 2 have been utilized in the ring-closing metathesis (RCM) of dienes containing gem-disubstituted olefins to yield tri- and tetrasubstituted cyclic olefins. Dienes with sterically demanding and/or electron-withdrawing substituents such as Ph, CO2Me, and tBu were cyclized successfully with 2, but did not cyclize with 1. Tetrasubstituted cyclic olefins could be formed with 2, but not using alkylidene 1. Dienes with allylic functional groups yielded functionalized cyclic olefins when treated with 1.
- Kirkland, Thomas A.,Grubbs, Robert H.
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p. 7310 - 7318
(2007/10/03)
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