- Synthesis and anti-HIV evaluation of new acyclic phosphonate nucleotide analogues and their bis(SATE) derivatives
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This article describes a very simple route for synthesizing novel lipophilic phosphonate bis(t-bu-SATE) prodrugs of acyclic cyclopentenylated nucleosides such as adenine 17 and cytosine 18. The key intermediate 6 was constructed via a ring-closing metathesis of compound 5, which could be readily prepared from diethylmalonate 4. The chemical stability of the bis(SATE) derivatives was tested at neutral (pH = 7.2) and slightly acid (milli-Q water, pH = 5.5) pH. The synthesized compounds were evaluated as potential antiviral agents against HIV-1 virus.
- Li, Hua,Hong, Joon Hee
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- Ruthenium Removal Using Silica-Supported Aromatic Isocyanides
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New silica gel scavengers containing aromatic isocyanides have been synthesized and evaluated for Ru removal. A thiol-ene click reaction was used to attach the isocyanide precursor to a thiol-containing siloxane. Conventional methods for grafting to silica gel at elevated temperature resulted in significant hydrolysis of the isocyanide. A novel cleavage reaction was developed to quantitate the amount of surface-loaded isocyanide. Binding by the new materials was comparatively evaluated for a variety or Ru carbene catalysts. The optimal conditions were extended to two ring-closing metatheses (RCM). The residual Ru was determined by inductively coupled plasma mass spectrometry (ICP-MS). For facile RCM reactions, the UV data agreed with the ICP-MS results. However, more difficult RCM did not correlate well with the UV data. This was interpreted in terms of varying extent of catalyst decomposition. In all cases, isocyanide scavenger reagents were found to be superior to commonly used, silica gel-based metal scavengers.
- Gregg, Zackary R.,Glickert, Elise,Xu, Ruoshui,Diver, Steven T.
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supporting information
(2021/05/13)
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- Conformational Control of Initiation Rate in Hoveyda-Grubbs Precatalysts
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When the coordinating isopropyl ether of the Hoveyda precatalyst is replaced by a cyclohexyl ether, it is possible to control the substituent's conformation in either the equatorial or axial position. A stereodivergent synthesis of axial and equatorial cyclohexyl vinyl ethers provided access to new ruthenium metathesis precatalysts by carbene exchange. The conformational disposition of the coordinating aryl ether was found to have a significant effect on the reactivity of the precatalyst in alkene metathesis. The synthesis of four new Ru carbene complexes is reported, featuring either the 1,3-bis(2,4,6-trimethylphenyl)dihydroimidazolylidene (H2IMes) or the 1,3-bis(2,6-diisopropylphenyl)dihydroimidazolylidene (SIPr) N-heterocyclic carbene ligand. The conformational isomers in the SIPr series were structurally characterized. Performance testing of all new precatalysts in three different ring-closing metatheses and an alkene cross metathesis illustrated superior performance by the precatalysts bearing axial coordinating ethers. Initiation rates with butyl vinyl ether were also measured, providing a useful comparison to existing Hoveyda-type metathesis precatalysts. Use of conformational control of the coordinating ether substituent provides a new way to modulate reactivity in this important class of alkene metathesis precatalysts.
- Gregg, Zackary R.,Griffiths, Justin R.,Diver, Steven T.
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supporting information
p. 1526 - 1533
(2018/06/04)
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- Kinetic benchmarking reveals the competence of prenyl groups in ring-closing metathesis
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A series of prenyl-containing malonates are kinetically benchmarked against the standard allyl-containing congeners using a ruthenium benzylidene precatalyst for ringclosing metatheses. The prenyl grouping is found to be a superior acceptor olefin compared to an allyl group in RCM processes with ruthenium alkylidenes derived from terminal alkenes. The prenyl group is also found to be a highly competent acceptor for a ruthenium alkylidene derived from a 1, 1-disubstituted olefin in a RCM process.
- Bahou, Karim A.,Braddock, D. Christopher,Meye, Adam G.,Savage, G. Paul
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supporting information
p. 5332 - 5335
(2017/11/07)
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- ANTIDIABETIC TRICYCLIC COMPOUNDS
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Novel compounds of the structural formula (I), and the pharmaceutically acceptable salts thereof, are agonists of G-protein coupled receptor 40 (GPR40) and may be useful in the treatment, prevention and suppression of diseases mediated by the G-protein-coupled receptor 40. The compounds of the present invention may be useful in the treatment of Type 2 diabetes mellitus, and of conditions that are often associated with this disease, including obesity and lipid disorders, such as mixed or diabetic dyslipidemia, hyperlipidemia, hypercholesterolemia, and hypertriglyceridemia.
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- Simple, chemoselective hydrogenation with thermodynamic stereocontrol
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Few methods permit the hydrogenation of alkenes to a thermodynamically favored configuration when steric effects dictate the alternative trajectory of hydrogen delivery. Dissolving metal reduction achieves this control, but with extremely low functional group tolerance. Here we demonstrate a catalytic hydrogenation of alkenes that affords the thermodynamic alkane products with remarkably broad functional group compatibility and rapid reaction rates at standard temperature and pressure.
- Iwasaki, Kotaro,Wan, Kanny K.,Oppedisano, Alberto,Crossley, Steven W. M.,Shenvi, Ryan A.
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supporting information
p. 1300 - 1303
(2014/02/14)
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- Ruthenium-catalyzed ring-closing metathesis to form tetrasubstituted olefins
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Figure presented Increased efficiency for ring-closing metathesis to form tetrasubstituted olefins using N-heterocyclic carbene ligated ruthenium catalysts was achieved by reducing the size of the substituants at the ortho positions of the N-bound aryl ri
- Berlin, Jacob M.,Campbell, Katie,Ritter, Tobias,Funk, Timothy W.,Chlenov, Anatoly,Grubbs, Robert H.
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p. 1339 - 1342
(2008/01/03)
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- Macrocycle formation by catalytic intramolecular cyclopropanation. A new general methodology for the synthesis of macrolides
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Catalytic intramolecular cyclopropanation by diazoacetates onto a remote carbon-carbon double bond resulting in the formation of 9- to 20-membered ring lactones is reported. When competition exists between proximal allylic and remote olefinic cyclopropanation, macrocyclization is favored by catalysts of increasing electrophilicity: Rh2(pfb)4 > Rh2(OAc)4, Cu(MeCN)4PF6 > Rh(cap)4, and Cu(acac)2. Terpene systems, cis-nerolidyl diazoacetate and related structures, malonic ester derivatives, and those with 1,2-benzenedimethanol, pentaerythritol, and cis-2-buten-1, 4-diol linkers undergo cyclopropanation onto the most remote carbon-carbon double bond in good yield. Generally, only one cyclopropane diastereoisomer is observed but increasing ring size allows stereochemistries in macrocyclization reactions that resemble those of their intermolecular cyclopropanation counterparts, In one system (25) macrocyclic addition is accompanied by ylide formation/[2,3]-sigmatropic rearrangement resulting in the formation of a 10-membered ring lactone. Overall, few limits to macrocycle formation are evident, and the methodology appears to have general applicability.
- Doyle, Michael P.,Peterson, Chad S.,Protopopova, Marina N.,Marnett, Alan B.,Parker Jr., Dann L.,Ene, Doina G.,Lynch, Vincent
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p. 8826 - 8837
(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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- Oxovanadium-induced or -catalyzed oxidative allylation of 1,3-dicarbonyl compounds with allylsilanes
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The oxidative mono- or di-allylation reaction of 1,3-dicarbonyl compounds with allylsilanes was selectively achieved by treatment with VO(OEt)Cl2.
- Hirao,Sakaguchi,Ishikawa,Ikeda
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p. 2579 - 2585
(2007/10/02)
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