Chemists at The Scripps Research Institute (TSRI) in La Jolla, California, have invented a powerful method for joining complex organic molecules. This method is extraordinarily robust and can be used to make pharmaceuticals, fabrics, dyes, plastics, and other materials previously inaccessible to chemists. “We are rewriting the rules for how one thinks about the reactivity of basic organic building blocks, and in doing so we’re allowing chemists to venture where none has gone before,” said Dr. Phil S. Baran, the Darlene Shiley Chair in Chemistry at TSRI, whose laboratory reported the finding on functionalized olefin cross-coupling in an online article in Nature published on December 17, 2014. With the new technique, scientists can join two compounds known as olefins to create a new bond between their carbon-atom backbones. Carbon-to-carbon coupling methods are central to chemistry, but until now have been plagued by certain limitations: they often fail if either of the starting compounds contains small, reactive regions known as “functional groups” attached to their main structure. They also frequently don’t work well in the presence of “heteroatoms”—non-carbon atoms such as nitrogen, oxygen and iodine—despite the importance of these types of atoms in chemical synthesis. The new method is what chemists call “mild,” meaning that it doesn’t require the use of extreme temperatures or pressures, nor harsh chemicals. As a result, portions of the building blocks used that are particularly fragile remain unaltered by the reaction. “Functional groups that would be destroyed by other cross-coupling methods are totally unscathed when using our method,” said Julian C. Lo, a graduate student who was a co-lead author of the report with Research Associate Dr. Jinghan Gui.
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