For years, the chemistry community has recognized the importance and utility of olefin metathesis. Now, the Royal Swedish Academy of Sciences has chosen to recognize it, too: Last week, the academy awarded the 2005 Nobel Prize in Chemistry to three chemists who developed the reaction—Yves Chauvin of the French Petroleum Institute, Rueil-Malmaison, France; Robert H. Grubbs of California Institute of Technology; and Richard R. Schrock of Massachusetts Institute of Technology. They will share equally the $1.3 million prize.
The Swedish academy's choice "confirms what is generally agreed upon in the synthetic chemistry community—that olefin metathesis is a very useful catalytic reaction that has a broad scope," comments Harvard University chemistry professor and Nobel Laureate Elias J. Corey.
In olefin metathesis, two carbon-carbon double bonds react to form two new carbon-carbon double bonds. In the process, substituents attached to the carbon atoms involved are exchanged. This exchange can result in various outcomes, including straight swapping of substituents, closure of large rings, formation of dienes, and polymerization. The reaction, which is catalytic, takes place under mild conditions and is so general that it is widely applicable.
The reaction was first observed in the 1950s, but it wasn't until 1971 that a convincing mechanism was proposed. Chauvin and student Jean-Louis Hérisson suggested that the reaction is initiated by a metal carbene, which reacts with an olefin to form a new olefin and a new metal carbene, which propagates the reaction. Other chemists shed further light on the mechanism, which put the reaction on the path of practicality. For example, work in 1975 by Columbia University chemistry professor Thomas J. Katz and graduate student James McGinnis led them to synthesize discrete metal-carbene complexes, which they used to initiate the reaction (C&EN, Dec. 23, 2002, page 34).
With improvements in metal-carbene initiators, the reaction became more widely used. Schrock and Grubbs led efforts to develop the catalysts that now allow olefin metathesis to flourish. Schrock's catalysts are based on molybdenum; Grubbs's are based on ruthenium and are widely credited with having put olefin metathesis in the hands of synthetic chemists because the catalysts are easy to use. "Chemists now routinely use the catalysts to prepare pharmaceutical candidates and new materials in an efficient and environmentally friendly way," says Jeremy M. Berg, director of the National Institute of General Medical Sciences, which has supported the research of the American winners.
In research, olefin metathesis has become a go-to reaction for constructing carbon-carbon double bonds, especially in complex molecules. In industry, the reaction is used in cleaner, less expensive, and more efficient production of polymers, pesticides, fine chemicals, and pharmaceutical intermediates and active ingredients (C&EN, Dec. 23, 2002, page 29).
According to the Swedish academy, olefin metathesis is a "great step forward for 'green chemistry.' " That statement reinforces the message that the best chemists in the world are doing green chemistry and that green chemistry is simply part of doing good chemistry, says Paul T. Anastas, director of the American Chemical Society's Green Chemistry Institute.
Olefin metathesis is "an example of how important basic science has been applied to the benefit of man, society, and the environment,"; the academy adds. Yet,"basic research is not recognized as much as it should be today," said Schrock at an MIT press conference last week. He and Grubbs, he said, "had faith that we were doing something new and that applications would develop, and they have."
Olefin metathesis catalysts and technology are available from Materia, a company based in Pasadena, Calif., that was founded by Grubbs and for which both Grubbs and Schrock are scientific advisers.
Read C&EN's definitive coverage of the Nobel Prize winning work on olefin metathesis.
Olefin Metathesis: Big-Deal Reaction
A boon to organic synthetic chemists, olefin metathesis also proves useful for many industrial processes through metal-carbene catalysts.
Olefin Metathesis: The Early Days
Recognizing the role of metal carbenes was key in realizing the promise of olefin metathesis.