Asymmetric Synthesis with Chiral Heteroalkyl Radicals

Case Western Reserve University, Cleveland OH

Investigators

Abstract

With the support of the Organic and Macromolecular Chemistry Program, Professor Philip P. Garner, of the Department of Chemistry at Case Western Reserve University, is studying asymmetric synthesis using chiral heteroalkyl radicals. Professor Garner is both developing a general, iterative polymer-supported radical synthesis of polyols and extending the use of pyranosidic chiral auxiliaries to synthetically useful closed-shell processes. The optimal resin-linker strategy for this iterative approach will be defined and techniques developed for the quantification of polymer-supported reactions. Methods for reducing the number of steps required for each iteration of the radical homologation sequence and paring down the structure of the chiral auxiliary will also be explored. Pyranosidic chiral auxiliaries will be applied to a variety of useful closed-shell processes. Concerted cycloadditions, allylboron/enolate alkylations, and a tandem asymmetric hydroboration/Suzuki coupling sequence will be examined, both in solution and on polymer supports. While organic reactions have traditionally been carried out in solution, allowing intimate mixing of reactants, there are many advantages to finding reactions in which either a reactant or a reagent is linked to an insoluble "support." If a spent reagent is attached to such a support, for example, it may be easily removed from the reaction mixture, while if a desired compound is attached, impurities may be easily washed away. Professor Philip P. Garner, of the Department of Chemistry at Case Western Reserve University, is supported by the Organic and Macromolecular Chemistry Program for his efforts in this area. Professor Garner is harnessing the reaction chemistry of compounds containing an unpaired electron ("radicals"), finding ways to control their reactivity so as to allow precise geometrical control over the products of their reactions.