As an approach to the common synthetic problems of selectivity, yield optimization, ease of product isolation, and efficiency with regard to use of expensive reagents, it is planned to explore the application of functionalized polymer systems to complex problems in organic synthesis. The principle of covalent substrate anchoring to control chemoselectivity has already been successfully demonstrated in the context of intermolecular Pauson-Khand cycloaddition. This work will first be expanded to intramolecular systems to establish its scope and range. It will then be extended to several diverse synthetic processes. Polymer linkage of nitroalkanes will be studied to control tandem cycloaddition/electrophilic cyclizations of nitrile oxides with alpha, omega-dienes, permitting stereocontrolled synthesis of differentially substituted cyclic ethers. Next, polymer methodology will be applied to asymmetric synthesis by covalent attachment of chiral auxiliaries to enhance chemical yields, improve optical yields, and simplify recovery of the chiral auxiliaries. Pauson-Khand systems will be tested as routes to optically pure polyquinanes, using polymer-bound chiral alcohols. Polymer-bound chiral oxazolines will be used as auxiliaries in stereoselective aza-Claisen rearrangements to generate optically active 4-pentenoic acids. Finally, a range of polymer-bound systems of C2-symmetry will be developed as means to approach the synthesis of a variety of differentially functionalized nonracemic synthetic systems. The Organic Synthesis Program is supporting this joint project between Dr. Neil Schore and Dr. Mark Kurth to develop new synthetic reagents that are based upon polymers. The former's background in organometallic and polymer chemistry is being melded with the latter's background in the synthesis of complex organic molecules. These new synthetic reagents will simplify techniques and lead to more economic and convenient syntheses.
