Issue Date: January 15, 2007
Herbert C. Brown Award for Creative Work in Synthetic Methods
Sponsored by the Purdue Borane Research Fund and the Herbert C. Brown Award Endowment
"Without David A. Evans, the art of synthetic methods development would not only be a far less advanced discipline than it is today, it would have a much less attractive future as well," says Amir H. Hoveyda of Boston College. Evans, a professor of chemistry and chemical biology at Harvard University, has developed a huge armamentarium of invaluable synthetic methods, Hoveyda points out. But Evans' far more lasting contribution, Hoveyda says, is that he "has trained some of the world's most exciting young scientists, many of whom are hailed as being the future leaders in the field of synthetic methodology."
Evans, 65, has built a career on achieving absolute stereocontrol in carbon-carbon bond-forming reactions. Although he has made invaluable contributions to organosilicon and organosulfur chemistry and developed new sigmatropic rearrangements and hydride reduction reactions, Evans remains best known for devising a family of widely used chiral auxiliaries for enantioselective bond construction.
When Evans demonstrated the utility of his now-legendary chiral oxazolidinone auxiliary system in the late 1970s, it was a dramatic departure from the then-widespread reliance on appropriate chiral building blocks to control the target structure's stereochemistry.
Bolstered by their availability and flexibility, Evans' chiral oxazolidinone auxiliaries quickly caught on, and today they are widely used in both industrial and academic laboratories for enantioselective bond constructions. These auxiliaries "served as the springboard for the development of a large array of new stereoselective methods," Hoveyda notes. They have allowed chemists to carry out a wide range of asymmetric reactions, including aldol additions, alkylations, acylations, oxygenations, halogenations, aminations, Diels-Alder cycloadditions, Staudinger reactions, and conjugate additions.
"Evans' chiral oxazolidinones and associated methodology have arguably been used more broadly than any other asymmetric method in natural product synthesis and pharmaceutical agent discovery," claims Jonathan A. Ellman of the University of California, Berkeley.
Evans later went on to develop chiral bis-oxazoline ligands for enantioselective catalysis. His lab has used their signature copper bis-oxazoline catalysts to drive a wide variety of enantioselective transformations, including olefin cyclopropanation and aziridination, aldol additions of silylketene acetals, and Diels-Alder reactions.
Throughout his career, Evans has demonstrated the power of his asymmetric methods by using them to construct complex natural products. "Evans belongs to that elite group of organic chemists who lead the way in both methods development and complex molecule synthesis," Hoveyda notes. Evans' lab has exploited the asymmetric reactions they have developed to conquer the synthesis of a whopping 50 or so natural products, including the glycosylated antibiotic vancomycin and the anticancer agent bryostatin.
Born in Washington, D.C., Evans received his bachelor's degree from Oberlin College in 1963 and his Ph.D. from California Institute of Technology in 1967. He was a faculty member at UCLA and Caltech before moving to Harvard in 1983. A recipient of numerous honors, including ACS's Arthur C. Cope Award in 2000, Evans is a member of the National Academy of Sciences and the American Academy of Arts & Sciences.
The award address will be presented before the Division of Organic Chemistry.
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