Synthesis, characterization and applications of novel polyethylene glycols in organic chemistry

Polyethylene glycols (PEG'S) are commonly used as polymer supports in organic and biochemistry, but the use of PEG'S is complicated by their inherent low loading capacities. We have developed a number of synthetic approaches allowing for the simple, large-scale synthesis of branched, dendrimeric and other high-loading polymer supports, based on PEG'S with the number of terminal hydroxyls ranging from 3 to 18. While the chemical properties of the new compounds were improved, they retain the original solubility properties of PEG rendering these materials attractive in many chemical, engineering and medical fields. Such advantages include low cost, high solubility in a variety of solvents, easy precipitation and analysis. The loading levels of these novel PEG's were investigated using a variety of spectroscopic and chemical methods.; Applications of both commercial and modified PEG's as trapping agents for photochemically generated carbenes were investigated. It was found that these modified PEG's exhibited increased efficiency as polymer supports in photochemical reactions, while attempts of inducing chiral enrichment in the trapped carbene using modified PEG with chiral auxiliary groups and various chiral alcohols remained unsuccessful.; Novel applications of PEG as a recoverable polymer support in enantioselective and stereoselective Sharpless oxidations were investigated.; Development and testing of various PEG-supported Sharpless epoxidation catalysts yielded mixed results. Soluble polymer-supported reactions showed ee's of only 41% and lower, while reactions mediated by insoluble tartaric acid and pentaerythritol ethoxylate-based polymer supports showed ee's of up to 79%.; Utilizing a number of different linkers, both new and known PEG-based cinchona analogues were synthesized and their use in Sharpless chiral amino-hydroxylation of trans-alkenes was investigated. The induced regioselectivity (up to 1:4) and stereoselectivity (ee's of up to 83%) were found to be comparable to those when commercial cinchona catalysts are used. Influence of the linker groups on the outcome of the reaction is discussed. These new PEG-bound cinchona alkaloids can find wide applications in industry as recyclable and environment-friendly aminohydroxylation catalysts.