Greening Organic Synthesis: Medicines, Materials, and More!
Fall 2014 - Written by Resnick Fellow Yiyang Liu
The advancement of synthetic organic chemistry has greatly expanded the chemist’s toolbox and facilitated discovery and development of drugs that target a broad range of diseases from cancer to HIV. In particular, metal-catalyzed organic reactions have seen exponential growth during the past two decades. These reactions are expert at joining two fragments into one molecule—a central task in organic synthesis.
Despite remarkable achievements in metal-catalyzed reactions, the vast majority of them rely on precious metals such as palladium and rhodium. Their supply is so limited that there is concern about these metals running out in the next few decades. In addition, almost all precious metals are toxic to the human body. These key disadvantages have prompted chemists to ask if we can perform organic reactions with earth abundant metal catalysts instead of using precious metals.
Caltech chemists Bob Grubbs and Brian Stoltz are dedicated to addressing this challenge, along with their lead researcher, graduate student and Dow-Resnick Fellow Anton Toutov. They have collaborated on developing a reaction to replace a hydrogen atom in an organic molecule with a silicon group. Remarkably, this very challenging reaction is catalyzed by a salt of potassium—a cheap and nontoxic metal. The products of this reaction are key building blocks in medicinal chemistry and drug design. No less important is the robustness and easy scalability of the reaction, making it possible to perform it on a fairly large scale in a moderate-sized flask.
“Not only is it academically very interesting, but this new chemical technology is greener, more efficient, and hundreds if not thousands of times less expensive than the current state of the art. We're really excited about this!” said Toutov, who first discovered the reaction in 2013. Wen-bo Liu, a postdoctoral scholar in the Stoltz Group, said, “It’s a unique method to make a carbon silicon bond and people will appreciate it because it allows for the syntheses of chemical compounds en route to pharmaceuticals through an operationally simple process.”