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May 23, 2011 - Volume 89, Number 21
- p. 33
Science & Technology Concentrates
More Science & Technology Concentrates
- Safer Synthesis Of Fluorophosphate Crystals
- Method for making analogs of metal oxides avoids hydrofluoric acid
- Biomass Burning Generates Isocyanic Acid
- Mass spectrometry method detects part-per-trillion levels of inflammation agent
- C-C Protein Crosslink Creates Substrate Pocket
- Novel structure found in microscopic algae protein
- Weak Acids Irritate Ion Channel
- Mechanism identifies action of acetic acid on cell membrane
- Metathesis Catalyst Catches A Few More Zs
- Revised version of ruthenium catalyst improves selectivity for Z alkenes in olefin metathesis reactions
- Spotting Clotting
- Detection strategy for blood clot regulator combines oligonucleotide, fluorescent probe and reversible inhibitor
- Molecules Vanish In Nanotubes
- Molecular dipoles induce mirror-image nanotube dipole that screen molecules from IR light
- Natural Halocarbon In Boar Meat
- Fungi chemical could aid understanding of halogenated pollutants
Topics Covered
More Science Stories
October 24, 2011
Bryostatins Retain Promise
(October 24, 2011 | Vol. 89 Issue 43 | pp. 10-17)New results in total synthesis reinvigorate a 40-year-old field of research.
For Cave's Art, An Uncertain Future
(October 24, 2011 | Vol. 89 Issue 43 | pp. 38-40)Disagreement on conservation course of action complicates a potential reopening.
Cancer Stem Cells
(October 24, 2011 | Vol. 89 Issue 43 | pp. 41-43)Researchers zero in on the pathways that allow cancer to bounce back after treatment.
What's That Stuff? Blue Jeans
(October 24, 2011 | Vol. 89 Issue 43 | p. 44)Making the iconic pants requires both color-addition and color-removal chemistry.
Shedding Nanoparticles
(October 24, 2011 | Vol. 89 Issue 43 | p. 5)Materials Science: Chemists observe metal objects sloughing off ions to form nanoparticles.
Modifying Messenger RNA
(October 24, 2011 | Vol. 89 Issue 43 | p. 7)Chemical Biology: Methylated bases in mRNA may have roles in gene regulation and obesity.
Lab-On-A-Chip For Planets, Moons
(October 24, 2011 | Vol. 89 Issue 43 | p. 8)Microfluidics: Automated chip is designed to detect extraterrestrial amino acids.
New Editor For Analytical Chemistry
(October 24, 2011 | Vol. 89 Issue 43 | p. 9)Publishing: Jonathan Sweedler to take the helm.
Science & Technology Concentrates
(October 24, 2011 | Vol. 89 Issue 43 | p. 37)
October 17, 2011
Improving Shop Safety
(October 17, 2011 | Vol. 89 Issue 42 | pp. 56-57)Yale updates policies on machine shop use after student death.
Cleaning Acrylics
(October 17, 2011 | Vol. 89 Issue 42 | pp. 58-59)Conservation scientists seek new ways to keep modern paintings looking their best.
Detecting H2S In Vivo (Member Content)
(October 17, 2011 | Vol. 89 Issue 42 | p. 60)Studies could lead to sensitive and selective analyses for tiny signaling agent.
Rules For Design
(October 17, 2011 | Vol. 89 Issue 42 | p. 9)Materials Science: Guidelines predict structures formed by nanoparticles and DNA linkers.
Identifying Modified Cells
(October 17, 2011 | Vol. 89 Issue 42 | p. 11)Molecular Biology: Technique tags and enriches cells genetically altered by nucleases.
Linker-Free Molecular Wires
(October 17, 2011 | Vol. 89 Issue 42 | p. 12)Electronics: Metal-carbon bonds increase electrical conductance.
Asymmetry From A Guest
(October 17, 2011 | Vol. 89 Issue 42 | p. 13)Stereochemistry: Enzymelike pocket that hosts chiral species controls catalyst's enantioselectivity.
Science & Technology Concentrates
(October 17, 2011 | Vol. 89 Issue 42 | pp. 54-56)
Z has become an ever more important letter for olefin metathesis with the advent of a ruthenium catalyst that is highly selective for preparing Z (cis) alkenes (J. Am. Chem. Soc., DOI: 10.1021/ja202818v). In the beginning, nearly all ring-opening and cross-metathesis catalysts predominantly yielded E (trans) alkenes. That began to change when MIT’s Richard R. Schrock and Boston College’s Amir H. Hoveyda led a team that developed highly Z-selective molybdenum and tungsten monoaryloxide-pyrrolide catalysts (C&EN, Sept. 13, 2010, page 33). Caltech’s Robert H. Grubbs and coworkers subsequently reported a ruthenium version featuring an N-heterocyclic carbene (NHC) ligand, but its Z-selectivity wasn’t quite on par with the Schrock-Hoveyda catalysts (C&EN, Nov. 15, 2010, page 37). Grubbs and Koji Endo are now reporting a revised version in which an adamantyl substituent on the NHC ligand is additionally coupled to the ruthenium center (shown above, R = tert-butyl). The resulting chelated structure improves the catalyst’s selectivity so that it’s comparable with molybdenum and tungsten catalysts. All of the Z-selective catalysts are welcome, Grubbs and Endo note, because they are each distinctly versatile for preparing complex natural products and stereoregular polymers.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © 2011 American Chemical Society
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