Special versatility of new catalytic method affects the Alzheimer's disease, cancer, autoimmune disease research

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A new catalytic chemical method for the synthesis of a large and important class of carbon carbon double bond was developed by scientists from Boston College and MIT, the team reported in the journal nature. The results extend the versatility of a set of metal-based catalysts much discovered only by researchers three years ago.

With molybdenum in the core, the catalysts have now demonstrated create, the higher energy isomers of an alkene molecule from two simpler and much more easily accessible terminal versions, the team reported in an article in the current issue of the magazine.

Carbon carbon double bonds also known as alkenes or olefins, exist in many medically relevant and bioactive molecules. Co-author Richard Schrock shared 2005 Nobel Prize in chemistry for the discovery of one of the earliest types of olefin metathesis catalysts.

Alkenes are available as the zig-zag shaped TRANS olefin, or the E-isomer, or the higher energy-Z while others take the form of "U" the CIS alkene isomers. Catalytic methods for the synthesis of alkenes Z, in particular by olefin metathesis, had attempted by many research groups in the world after but so far turned out to be elusive, said Amir Hoveyda, the lead author of the paper and the Joseph t. and Patricia Vanderslice Millennium Professor of chemistry at Boston College.

Z isomers require a catalyst that promote chemical reaction while retaining the CIS be olefin U-shape geometry must be sufficiently active. Conservation both features in catalyst leading to reactions, the Z-alkenes, which you see a large number of medically important molecules and serve most transformations in chemistry provide commonly used as starting materials for some.

"This higher energy of carbon carbon double bond incredibly important, chemist and researcher in various fields such as medicinal chemistry, chemical biology, organic synthesis and materials research," said Hoveyda. "The trick here was to come up with a catalyst that promote education is active enough Z-alkene but not to actively to want to react with the product." So, in a way, we had to go on a very tight rope. Olefin metathesis is a reversible reaction and you always risk isomer goes back and forth between product and raw material, which forces you to with a lower energy and less desirable at the end. "Catalysts are what we have found that are sufficiently active to promote this difficult response enough not to go but also discriminatory, after the product and cause the isomerize."

With the very abundant and low-cost metal molybdenum, Hoveyda and his colleagues show the catalyst can produce a Z selective "Cross metathesis" reaction - an olefin metathesis reaction in which two different alkene-containing molecules in a single molecule, generate only ethylene are merged, the smallest possible alkene-containing molecule, as the byproduct. Simply by their reactions run in a vacuum, the team discovered that removing generated olefin can greatly improve the desired process and yield unprecedented reactivity and selectivity.

The researchers showed the particular versatility of new catalytic method by synthesis of a strong antioxidant Plasmalogen Phospholipid, molecules for cellular function of vital importance, which have brought Alzheimer's disease, as also the strong Immunostimulant KRN7000, has been shown to combat tumors in context, Autoimmune disease and graft - versus - host disease in mice.

The synthesis of such biologically relevant molecules on the far-reaching importance of olefin metathesis proves Hoveyda said. In the case of the anti-oxidant, the endpoint when establishing the connection marked the carbon carbon double bond. For the Immunostimulant, the creation of the double bond Z was most critical in subsequent structural changes required to achieve the final goal.

Source:
Ed Hayward
Boston College