Professor Theodore Cohen, of the Department of Chemistry at the University of Pittsburgh, is supported by the Organic and Macromolecular Chemistry Program for his studies of metallo-ene cyclization reactions. Both the insertion of titanocene into allyl phenyl sulfides and the tandem additions of homoallyl and bis(homoallyl) metals to dienes afford substrates for titana-ene cyclizations. These are carried out stoichiometrically, but may be adapted for the cyclopolymerization of conjugated dienes through the use of excess diene, affording robust ladder polymers. This work is complemented by Professor Cohen's investigation of allyl phenyl sulfides as substrates for the preparation of allyl Grignard reagents, which in turn permit the synthesis of a wider variety of substrates for metallo-ene cyclizations. Reductive lithiation of phenylthioethers affords homoallyl- and bis(homoallyl)lithiums, offering access to anion-accelerated ene cyclization reactions through their addition to dienes. With the support of the Organic and Macromolecular Chemistry Program, Professor Theodore Cohen, of the Department of Chemistry at the University of Pittsburgh, is developing new and efficient methods for the synthesis of cyclic organic compounds. Through the discovery and exploitation of new reactions of particular classes of organometallic compounds (compounds containing bonds between metal and carbon atoms), Professor Cohen readily accesses complex cyclic structures of utility in the synthesis of natural products and fine chemicals. These reactions may be readily adapted to permit the synthesis of `ladder` polymers which display important physical and chemical properties, such as heat and chemical resistance, imparted by their unique structural features.
