Sulfur fluoride exchange—a powerful new reaction for click chemistry
The coupling of molecular building blocks nearly as easy as “snapping” them together can be realized by means of the “click chemistry” tool kit. American scientists have now introduced another achievement for the click concept in the journal Angewandte Chemie: the sulfur fluoride exchange reaction (SuFEx) can be used to form robust inorganic bridges between carbon centers and opens up a fully unexplored area of chemistry with countless new molecules that could form the basis for new drugs, diagnostics, plastics, “intelligent” materials, and many other products.
Developed in the 1990s by Nobel Laureate K. Barry Sharpless and his colleagues, the concept of click chemistry is aimed at synthesizing target molecules rapidly and precisely from smaller units. The reactions must be specific, broadly applicable, and environmentally friendly while delivering high yields.
They must also be based on inexpensive, widely available reagents that react under mild and uncomplicated conditions. Since the discovery of the azide–alkyne cycloaddition reaction in 2002 by the Sharpless team, the click concept has become established as a universal chemical technique.
A team led by Sharpless at The Scripps Research Institute in La Jolla (CA, USA) has now developed another groundbreaking click reaction: sulfur fluoride exchange (SuFEx). This reaction exploits the very special reactivity of sulfur fluorides and makes it possible for chemists to bind together molecules of their choice.
Like most click reactions, the process itself is an old one that has been improved to allow the previously underestimated sulfate bond to be used as a universally applicable connector for linking a variety of molecular building blocks.
The starting material is a common, commercially available chemical called sulfuryl fluoride (SO2F2) that is widely used as a fumigant against termites and other pests. It was previously considered generally inert—incorrectly, as Sharpless and his co-workers have found. The team was able to make this chemical reactive in a reliable and predictable way.
In the SuFEx reaction, the fluoride ion must be extracted from a bond with a hexavalent sulfur atom. This is not so easy, so the SO2—F unit is remarkably stable in typical acidic or basic environments. This bond thus fulfills a central requirement of click chemistry: it remains “invisible” under most conditions, coming to life only on demand.
A broad palette of potential applications could benefit from this reaction. The teams of Sharpless and V. V. Fokin developed an efficient, nearly quantitative synthesis of high-molecular-weight polysulfate polymers that should be easy to implement on an industrial scale. Linked by sulfate groups, these polymers are sulfur-containing analogues of polycarbonates and represent a new class of plastics potentially superior to present-day materials.
One particular advantage is that unlike polycarbonates, which can react with water to give off bisphenol A—a substance that has hormonelike properties and poses problems for both health and the environment—polysulfates are resistant to hydrolysis and thus cannot release monomers.
This is just one application for the SuFEx reactions; many other reactions with other building blocks are possible. An advantage for the biological sciences is that sulfate links do not occur in any life forms and the new SuFEx reaction does not interfere with biological processes.
About the Author
K. Barry Sharpless, W. M. Keck Professor at The Scripps Research Institute and its Skaggs Institute for Chemical Biology, pursues and develops useful new chemical connectivity. Click chemistry was conceived by him in the mid-1990s as a method for rapidly discovering, and improving existing, useful reactivity. Now his group has found its 2nd 'perfect' click reaction. In 2001 he shared the Nobel Prize in Chemistry for his work on asymmetric catalysis.
Author: K. Barry Sharpless, The Scripps Research Institute, La Jolla (USA), http://www.scripps.edu/sharpless
Title: Sulfur(VI) Fluoride Exchange (SuFEx): Another Good Reaction for Click Chemistry
Angewandte Chemie International Edition 2014, 53, No. 35, 9430–9448, Permalink to the article: http://dx.doi.org/10.1002/anie.201309399
K. Barry Sharpless | Angewandte Chemie
Gene switch may repair DNA and prevent cancer
12.02.2016 | Institute for Integrated Cell-Material Sciences at Kyoto University
New method opens crystal clear views of biomolecules
11.02.2016 | Deutsches Elektronen-Synchrotron DESY
Today, plants and microorganisms are heavily used for the production of medicinal products. The production of biopharmaceuticals in plants, also referred to as “Molecular Pharming”, represents a continuously growing field of plant biotechnology. Preferred host organisms include yeast and crop plants, such as maize and potato – plants with high demands. With the help of a special algal strain, the research team of Prof. Ralph Bock at the Max Planck Institute of Molecular Plant Physiology in Potsdam strives to develop a more efficient and resource-saving system for the production of medicines and vaccines. They tested its practicality by synthesizing a component of a potential AIDS vaccine.
The use of plants and microorganisms to produce pharmaceuticals is nothing new. In 1982, bacteria were genetically modified to produce human insulin, a drug...
Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock which attains an accuracy which had only been predicted theoretically so far. Their optical ytterbium clock achieved a relative systematic measurement uncertainty of 3 E-18. The results have been published in the current issue of the scientific journal "Physical Review Letters".
Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock...
The University of Würzburg has two new space projects in the pipeline which are concerned with the observation of planets and autonomous fault correction aboard satellites. The German Federal Ministry of Economic Affairs and Energy funds the projects with around 1.6 million euros.
Detecting tornadoes that sweep across Mars. Discovering meteors that fall to Earth. Investigating strange lightning that flashes from Earth's atmosphere into...
Physicists from Saarland University and the ESPCI in Paris have shown how liquids on solid surfaces can be made to slide over the surface a bit like a bobsleigh on ice. The key is to apply a coating at the boundary between the liquid and the surface that induces the liquid to slip. This results in an increase in the average flow velocity of the liquid and its throughput. This was demonstrated by studying the behaviour of droplets on surfaces with different coatings as they evolved into the equilibrium state. The results could prove useful in optimizing industrial processes, such as the extrusion of plastics.
The study has been published in the respected academic journal PNAS (Proceedings of the National Academy of Sciences of the United States of America).
Exceeding critical temperature limits in the Southern Ocean may cause the collapse of ice sheets and a sharp rise in sea levels
A future warming of the Southern Ocean caused by rising greenhouse gas concentrations in the atmosphere may severely disrupt the stability of the West...
12.02.2016 | Event News
09.02.2016 | Event News
02.02.2016 | Event News
12.02.2016 | Physics and Astronomy
12.02.2016 | Life Sciences
12.02.2016 | Medical Engineering