Richard D. Broene
Professor of Chemistry, Chair of Chemistry Department
Fall 2008
- Organic Chemistry I (CHEM 225A)
- Organic Chemistry I (CHEM 225B)
| Phone | (207) 725-3626 |
| Title | Professor |
| Department | CHEMISTRY |
| 2nd Title | Chair |
| 2nd Department | CHEMISTRY |
| Work Location | 50 Cleaveland Hall |
| rbroene@bowdoin.edu |
Education:
B.S. Chemistry, Hope College (1985)
Ph.D. Organic Chemistry, University of California, Los Angeles (1990)
Rick Broene received his BS in Chemistry from Hope College (Holland MI) in 1985 at which time he was was honored with a Sigma Xi summer research award. While at Hope he worked with Mike Doyle investigating the decomposition mechanism of trioxodinitrate(II) in the presence of metalloproteins. He went on to graduate school at UCLA, where he worked with Francois Diederich on the synthesis and study of molecules with high carbon to hydrogen ratios (graphite-like molecules) specifically, the synthesis of circumanthracene. While there he also helped to design and synthesized the first asymmetric podand to be used for molecular recognition. He received his Ph.D. in Organic Chemistry in 1990. In a complete change of direction after grad school, he was a postdoctoral fellow at MIT, where he studied organometallic chemistry. While there, he reported the first method for highly enantioselective reduction of unfunctionalized trisubstituted olefins and achieved diastereoselective syntheses of indoles, indolines, and isoquinolines using zirconocene intermediates. In 1998, Professor Broene was a Visiting Staff Member at Los Alamos National Lab in New Mexico. While at LANL, he continued to develop his interest in both homogeneous asymmetric catalysis while investigating the immobilization of catalysts on solid supports. This interest was expanded during the 2004-05 academic year when he was a visiting scholar at UNC Chapel Hill working the the broadly defined area of late transition metal catalyzed polymerization reactions. Research grants from the NSF, PRF, Research Corporation, CUR, Pfizer and DOE have enabled 44 students to work on projects in his labs over the past 14years.
Research Interests
Professor Broene's research interests focus on the use of transition and lanthanide-series metals to accomplish asymmetric organic syntheses, as well as the rational, metal-facilitated synthesis of ligands for chiral catalyts.
There are several projects currently underway in his research labs. The first investigates the ability of tethered bis-indenyl ligands to serve as proto-C2 symmetric ligands for lanthanide metals, forming metallocene complexes. The work in this area showed that the two-carbon tether was too short to allow the preferred formation of the racemic form of the complex, favoring instead the meso form. This is in part due to the large ionic radius of these f-electron elements. The group is currently synthesizing ligands with longer tethers to determine the optimal tether length for the formation of the complexes.
A second area investigates the use of large, rigid ferrocene backbones as supports for asymmetric ligands. Under development are ligands based on N-heterocyclic carbenes as well as sulfonamide functional groups.
Another area of interest is the use of metallocene intermediates to facilitate natural product syntheses. The zirconium-mediated diastereoselective synthesis of some necine alkaloids such retronecine serve test cases. The general synthetic route utilizes the reductive coupling of a diene using well established zirconium chemistry. Through molecular modeling studies using "Spartan", it is predicted that the transitions states leading to the two diastereomeric necines will differ by more than 3 kcal, allowing the reaction to give very high diastereoselectivities.
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