High Symmetry Catalysts in Organic Synthesis

Suny At Buffalo, Amherst NY

Investigators

Abstract

With the support of the Organic Synthesis Program, Professor Huw M. L. Davies, of the Department of Chemistry, State University of New York at Buffalo, is studying the use of high symmetry catalysts in organic synthesis. Coordination of several identical low-symmetry ligands around a central metal core leads to high-symmetry chiral complexes. Thus, dirhodium complexes bearing two C2-symmetric binaphthylphosphate ligands are D2-symmetric, while those with four binaphthylphosphate ligands are D4-symmetric. Three basic reaction types catalyzed by such complexes are under investigation. Highly stereoselective asymmetric C-H activation is effected by means of intermolecular carbenoid-induced C-H insertion. Combined C-H insertion/Cope rearrangement protocols lead to carbon-carbon bond formation with potential control of stereochemistry at two stereogenic centers and two double bonds. Finally, [3+2] cycloaddition between vinylcarbenoids and vinyl ethers generates highly functionalized cyclopentenes with excellent stereocontrol at three stereogenic centers. Many of the complex organic molecules displaying desirable properties as pharmaceutical agents contain groupings of atoms with precisely defined geometric ("stereochemical") relationships. These molecules may differ from undesired compounds through as seemingly subtle a relationship as that between one's left and right hands (i.e., mirror images), and the development of methods for the selective synthesis of such molecules remains a significant challenge. Professor Huw M. L. Davies, of the Department of Chemistry, State University of New York at Buffalo, is supported by the Organic Synthesis Program for his studies of new methods for the selective synthesis of such organic molecules. By the preparation of catalysts with carefully designed symmetry, Professor Davies effects a variety of reactions, particularly those involving the insertion of new carbon centers into carbon-hydrogen bonds, which allow for the construction of more complex products with a high degree of stereochemical control.