Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Better together

07.02.2011
Twin zinc atoms can direct an important organic double-bond-forming reaction with greater efficiency than other methods

Many natural compounds found in plant and animals display potent medicinal capabilities, but their intricate chemical structures prevent large-scale manufacturing.

One common difficulty is synthesizing carbon–carbon double bonds, or alkenes, on the exterior of a molecular framework—a reactive and relatively unstable location. Exposure of the exact mechanisms of an alkene-generating reagent with the moniker of gem-dizinc may resolve this problem, report Shinsuke Komagawa and Masanobu Uchiyama from the RIKEN Advanced Science Institute in Wako and their colleagues from Kyoto University and The University of Tokyo1.

To transform terminal carbon–oxygen double bonds, or carbonyl groups, into alkenes via a short-lived complex that connects two carbon atoms together, chemists classically turn to organophosphorus salts known as Wittig reagents. Sometimes, however, these reagents fail to react with carbonyls or give unwanted by-products, fueling a search for new substances with improved activity and better structural control.

gem-Dizinc compounds are Wittig-type reagents that can produce a wide range of terminal alkenes quickly and at room temperature. They consist of twin zinc atoms that sandwich a methylene (CH2) unit. Despite these synthetic advantages, the use of gem-dizinc reagents remains limited because their structures are unstable and their modes of action controversial; some mechanistic features have eluded discovery for nearly forty years.

Komagawa, Uchiyama, and their team tackled this challenge by first using detailed spectroscopic experiments to identify the active form of the metal complex. Dizinc compounds can readily react with each other to make dimers, polymers, or cyclic structures. However, their measurements conclusively demonstrated that the single monomer was the dominant chemical species.

The researchers took this information as the starting point for sophisticated density functional theory calculations of the reaction pathways. Their simulations showed that alkene formation takes place in two steps: initially, gem-dizinc adds to the carbonyl and forms a cyclic complex. Then, the carbon–carbon double bond is created after gem-dizinc swaps its methylene unit for an oxygen atom. They found that the key factor in making this process so efficient was a cooperative ‘push–pull synergy’ between zinc metals that drove the transformation without having to shuffle electrons between different atoms, making this process quicker than other approaches.

According to Komagawa, these results should help spur the logical design of even better complexes. “The comprehensive mechanistic knowledge acquired in this approach will drive the next stage of this chemistry—more efficient metal reagents that improve the yield and selectivity of alkene formation,” he says.

The corresponding author for this highlight is based at the Advanced Elements Chemistry Research Team, RIKEN Advanced Science Institute.

Journal information

1.Sada, M., Komagawa, S., Uchiyama, M., Kobata, M., Mizuno, T., Utimoto, K., Oshima, K. & Matsubara, S. Reaction pathway of methylenation of carbonyl compounds with bis(iodozincio)methane. Journal of the American Chemical Society 132, 17452–17458 (2010).

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://www.researchsea.com

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>